I've heard this term used to describe approaches into low weather (e.g. category 2 ILS), what is it? How is this different than an ILS approach?
A monitored approach is a special kind of instrument approach involving added verbal call outs and increased monitoring of the airplane and is typically conducted when weather is below a certain threshold. For example, a crew may be required to fly a monitored approach if the weather is below 3/4 mile vis and the captain has less than 100 hours in type, or in any case with the weather below ILS Category I minimums. It is also specific to multi-crew aircraft and requires at least 2 pilots and in many cases an autopilot.
In a crew environment, the pilots are typically designated as Pilot Flying (PF) and Pilot Not Flying (PNF). In general the PF is flying and making commands of the PNF, and the PNF mans the radios and operates gear and flaps the command of the PF. More detail of this setup probably deserves its own question.
To illustrate a monitored approach, I'll describe on based on my companies procedures. The specific requirements can vary between operators based on crew training, aircraft equipment and approved opspecs.
The monitored approach briefing
We have identified the arrival airport current weather is 1200 RVR and obscured ceilings and we plan to fly the ILS to category II minimums. Myself and my first officer have both have current category 2 training, neither of us are high-minimums, and the aircraft has no MEL items effecting category 2 operations. We are legal to fly the approach, but company operations require we fly it as a monitored approach.
Regardless of who has been PF and PNF up to this point, the first officer becomes the PF and the captain the PNF. The PF briefs the approach as normal except for:
- CAT II radar altitude minimums
- Low vis taxi routes if applicable
- The approach will be flown by the autopilot (company specific)
- Special autopilot considerations
- Required verbal call outs (see below)
The monitored approach
For my company, the autopilot had to be engaged in "CAT 2" mode before glideslope intercept. This will vary by aircraft and company. For the approach, as noted earlier, the first officer is PF, captain is PNF.
The PF duties are to monitor the autopilot and to execute the missed approach if the autopilot has problems. The PNF also monitors the autopilot. The pilots are monitoring the autopilot for performance and for indications it cannot meet required tolerances for the approach.
PF will call for gear and flaps as normal, except a non standard flap setting may be used for the approach (e.g. we flew flaps 22 instead of 45).
Once configured for landing, the PF will call for "Landing checklist - to the line" (company specific), this for us was the normal landing checklist with the caveat that the checklist is complete when the captain announces "Landing, I have the airplane" (more on this in a moment).
Nearing the Cat II decision height (typically 100 ft RA), the PNF will announce "Going heads up", discontinue monitoring the autopilot and look for the approach lighting system and the runway lights.
The PF will continue to monitor the autopilot.
The airplane will announce "Minimums" at the radar altitude DH and when the airplane reaches this height, the PNF will fly the missed approach.
If the captain sees the required lighting to continue the approach, they will announce "Landing, I have the airplane", and the FO will reply "you have the airplane, landing checklist complete.
The Captain must disconnect the autopilot (by 50 feet, no autoland for us), and would fly any aborted landing executed after taking control.
Rules on autopilot usage, disconnect heights and autolanding will vary based on aircraft and company policies. My example assumes an Embraer-145 certified for Cat 2 approaches and no autothrottles or autoland capability. Checklist verbiage and flap configurations mentioned also would vary by aircraft and company. And finally, the specific callouts will vary by company.
While it seems like there was a lot of Category II specific things in my example, the two concepts of reduced visibility ILS approaches and monitored approaches are intertwined, and you will almost always be flying a monitored approach because it is required to conduct the low weather approach by company policy.
"Monitored approach" is the most commonly used term for a specific allocation of pilot tasks during an approach to land. It involves a different distribution of workload to the traditional one, in which a single individual (the "pilot") is assigned all the aircraft handling tasks for instrument approach, visual landing and instrument go-around phases, as well as decision-making and overall management of the flight. The other individual - the "co-pilot" -is assigned the Pilot Monitoring tasks throughout.
In a "monitored approach", pilot duties are divided differently. One individual is responsible for overall management, decision-making, monitoring of all instrument flight during approach and go-around, and handling during the visual landing phase.
The other's responsibilities are aircraft handling during instrument flight (approach and go-around), and monitoring during visual flight.
Thus, the "co-pilot" controls the aircraft on approach exclusively ‘head down’ by reference to the flight instruments, whilst the "pilot" monitors and oversees the flight prior to either (a) assuming control for landing, or (b) continuing to monitor and manage in the event of a go-around being necessary.
This basic duty allocation has also been known by other terminology including but not limited to "delegated" , "pilot monitored" "split", "shared", or "control handover" approach.
A significant reason for these terminology variants is to accommodate concerns that limiting the application of the term "monitored approach" exclusively to this duty allocation implies that other duty allocations do not require the approach to be monitored, when there are clear obligations to do so.
Similarly, the term has occasionally been applied to a totally different concept, when the aircraft's approach is monitored by air traffic controllers on the ground using radar, in a radar-monitored approach or ground-monitored approach.
Consequently there has been ambiguity in the flight operations community about what is meant when the term "monitored approach" is used (see George Mason University study for FAA, 2004, page 7: "Ambiguity of the term").
For clarity, in the description and arguments sections here the term "Pilot-in-charge Monitored Approach" will be used for this purpose under the acronym "PicMA", as it specifies that the pilot in charge and responsible for the major flight decisions is performing the Pilot Monitoring tasks during the approach. Use of this term will encompass all known specific implementations of the procedure.
In the "history" section the term "monitored approach" in quotes will be used as it represents the terminology used in most references.
The abbreviation "P1" will be used for the "Pilot in charge", who is normally the pilot who has made the takeoff and is anticipating making the landing. "P2" means the other, second pilot or co-pilot.
The following description is of the most widely applicable implementation. Individual operators may use more restricted variants, as will be noted later. In "traditional" operations, it is normal for the Aircraft Commander to decide which pilot will undertake the "Pilot Flying" (PF) tasks and which the "Pilot Monitoring" (PM) tasks, in accordance with company-specific criteria. Typically this will then apply throughout the flight. In operations using PicMA, the same decision simply determines which pilot will undertake the "Pilot in charge" (P1) role and which the co-pilot (P2) role.
Prior to the commencement of the descent and approach, the crew perform the required approach and landing briefings to achieve a common understanding of the intended plan. For example the P2 may present a plan for the descent, approach and go-around, for acceptance or modification as appropriate by the P1. The P1 outlines intentions in relation to the landing conditions etc.
The P2 then assumes the Pilot Flying tasks, and the P1 the Pilot Monitoring tasks, including normal communications with Air Traffic Control. The P1 role includes overall management of the flight as Pilot in charge. During the approach all normal operator-specified callout tasks are made as and when appropriate.
Approaching the applicable Decision Altitude/Height (DA/DH) the P1 (monitoring) pilot starts seeking external visual references, with the objective of being in a position to announce a prompt decision at DH with an unequivocal call of either “Land” or "Go-Around".
At DH the P2, as "head-down" pilot, calls “Decide”. If the P1's response is “Go Around”, the P2, head-down pilot flies the prescribed or ad-hoc cleared missed approach, and the P1 continues in the pilot monitoring and management role. If the response to the "Decide" call at DH is “Land”, the P1, who previously been monitoring and has made that call, takes over as PF and continues to the landing. The P2 relinquishes control and continues with the monitoring tasks, with attention primarily devoted to continued monitoring of the instruments.
If visual reference should subsequently be lost below DH, or other circumstances call for a missed approach after the P1 has taken control - a baulked landing - then the P1 calls for and commences the go around. The P1 subsequently hands back control to the P2 a suitable point during the missed approach climb out, to consider options for completing the flight such as either another approach or a diversion.
For non-precision approaches, a "Continuous Descent Final Approach" with a Decision Height is normally recommended as safer than a "step-down" or "dive and drive" with a Minimum Descent Altitude/Height (MDA/MDH) and a Missed Approach Point. However PicMA procedures can be used for step-down procedures using an MDA/H, using a call by P2 of "maintaining minimum" (or equivalent) on reaching the MDA/H, with the Decide call being made at the Missed Approach Point. In this case the level portion of a step-down procedure will be flown more accurately and safely.
If all conditions for a safe landing laid down by the operator have been achieved well above DH, i.e. "stable approach criteria" are met and full visual reference has been established, the P1 may assume control at his/her discretion with a declaration of "visual, I have control" or equivalent. Depending on operator preferences, the P2 will be expected to continue instrument monitoring and make appropriate callouts.
Detailed ICAO Standards and Recommended Practices (SARPS) do not exist for crew cockpit duty allocations, hence significant variations can be found. The PicMA procedure as described can be applied to all categories of operation in both IMC and VMC, and all types of instrument approach.
The PicMA procedure concept is fully compatible with "leg and leg flying" and "role reversal", and does not impede the ability of First Officers to obtain either handling experience or experience for licensing purposes as "Pilot in Command Under Supervision".
Many operators use specific weather criteria to determine when to use a PicMA procedure. Typically in these cases the flight has started with the crew using "traditional" PF/PM duty allocations, and a decision to change to a PicMA procedure is made by the Captain on the basis of weather information received en route. Such weather criteria are generally based on reported or forecast visibility and cloud cover, and the degree of discretion afforded to the pilot in command in respect specific types of approach and/or prevailing weather conditions may also vary from operator to operator.
In North America, such criteria have tended to involve crew rank as a factor. It is often allied with the prevalence of conditions in which the First Officer is not normally authorised to make a landing. In such cases it may be mandatory for the First Officer to be the P2 to fly the approach/go around, and the pilot in command as the P1 to monitor the approach/land. This limitation is less often the case in Europe and elsewhere.
For Low Visibility Operations, authorities may approve variations in the point at which the pilot role change takes place depending on category of operation, e.g. Category 3 operations where an automatic landing is mandatory, or enhanced low visibility equipment such as Head Up Displays are required. Operators may also vary the degree of discretion afforded to the pilot in command in respect of using the method for specific types of approach and/or prevailing weather conditions.
Comparisons between "Traditional" and PicMA procedures
Air transport operations predominantly use approach procedures with no exchange of PF tasks. Aircraft manufacturers generally provide task-based operating procedures for individual aircraft types, which describe principally tasks for Pilot Flying and Pilot Not Flying/Pilot Monitoring. These are often then translated into Operators' own approved manuals with little modification.
As PicMA involves exchanging the tasks of PF and PM between pilots, it is often interpreted as being a significant departure from the manufacturers' recommendations, although in fact they may be silent or equivocal on the subject, or even support the use of PicMA in line operation. As a result, safety-based arguments can be found both for using PicMA procedures and for maintaining the status quo.
Although frequently thought to be only a "bad weather transition" procedure, the principal arguments in favour of using PicMA revolve around three main consequences of the redistribution of workload. These address the most common types of contributory causes in so-called "crew-caused" approach and landing accidents:
- inadequate planning and preparation for the conditions actually encountered;
- ineffectiveness of the monitoring of the Pilot Flying by the Pilot Monitoring
- inappropriate or premature attempts to transition from instrument to visual cues.
All these are extensively described in accident reports and have been the subject of large amounts of research, examples of which are given in the "history" section.
Planning and preparation. It is contended that when using PicMA procedures, approach management is improved by the PiC's delegation of detailed handling tasks. Starting with better crew interaction and teamwork in descent and approach planning, the P1's capability to maintain situational awareness is enhanced, and mitigates problems of communications and interpretation between crew and external agencies.
A lower routine workload provides more reserve capability for threat and error management. Having the flying assigned to the P2 on the approach, and with the P2 mentally preparing for a go-around not a landing, the risk of "plan continuation bias" leading to a dangerous landing attempt is reduced, as is the "startle factor" if a go-around is necessary.
Ineffective monitoring. For the second type of factor, it is contended that in all conditions, transferring the main monitoring task to the pilot actually in overall charge of the flight increases monitoring effectiveness. This is attributed to its reversal of the normal cross-cockpit authority gradient, and procedurally eliminating the "First Officer's dilemma" - whether to continue to assist the Captain in a course of action the F/O believes may be unwise, or actively oppose it.
It addresses commonly recognised cultural issues in traditional monitoring procedures by promoting monitoring as a fundamental active command role, which builds on strengths and reinforces weaknesses in both "authoritarian" and "individualistic" cultures. Accepting that "monitoring" means "supervision" and associating monitoring with accountability and authority encourages a conservative mind-set and discourages risk-taking.
Overall it is contended that this significantly reduces monitoring / challenging errors and provides better protection against "tactical errors" and "errors of omission".
Transition to visual cues. In the third type of contributory cause, unsafe transition from instrument information to external visual cues, especially in bad weather when approaching Decision Height / MDA, overall command capability is enhanced as the P1's situational awareness is better maintained through having to concentrate less on detail handling tasks. The maximum possible time is provided for assessment of developing visual cues, while premature transfer to visual cues which can be illusory is minimised.
There is more assurance of a positive decision being made at Decision Height, rather than below it. Unbroken monitoring of instruments can be assured as both pilots are not exposed to looking out at the same time. This enhances the detection of low altitude flight path deviations in a continued approach to landing, and the PM's callout reliability is also enhanced.
In a Go-around from DH, the PF is already fully attuned to instrument flying and "primed" for the go-around. Extensive references supporting these contentions have been collected and can be found at www.picma.org.uk.
By comparison, arguments are also made for maintaining the status quo. These fall into a number of areas - actual safety risks incurred, technical redundancy / irrelevance, and pilot satisfaction / conservatism. For the most part they are contentions whose proponents have not supplied supporting arguments or evidence, beyond the fact that the changes to the status quo are not generally supported.
It is contended that a low level exchange of control is inherently hazardous, due to factors such as
- a need for the P1 to get the feel of the controls,
- a need for the P1 to deal with out-of-trim conditions or unstable flight path conditions that have been accepted by the P2,
- risk of confusion as to who has control resulting in one pilot trying to go around while the other tries to land, and
- risk of loss of control during transition.
These concerns are not generally vindicated by analysis of accident reports. V
Very low level control exchange has been a factor in accidents, but these have almost all occurred as a result of a breakdown of "traditional" procedures leading to an unanticipated change of control in a situation which had already become unsatisfactory. There are no known examples of the changeover resulting in loss of control where the change of control had been planned for and agreed in advance.
It has also been contended that the use of PicMA would impose a long term risk as it would prevent First Officers landing from approaches flown at night or in IMC. This would conflict with policies aimed at having two pilots equally capable of monitoring each other, via complete role reversal in appropriate circumstances. Such a situation could arise as a result of operator-imposed restrictions based on rank, but it not relevant to or a characteristic of the PicMA procedure itself. This promotes such role reversal by the term "pilot-in-charge".
It is stated in some forums that PicMA is not relevant to current operations because technical developments have rendered it redundant. The thrust of this argument is that when the PicMA procedure was first being developed (see HISTORY below) many approaches had to be flown manually, or with very limited autopilot facilities and ground guidance. The contention is that the availability of high quality autopilots and improved ground and airborne systems such as GPS and HUD therefore renders a crew procedural solution to accidents redundant.
While the accident rate has significantly reduced over time, accidents and incidents continue to occur to all types of aircraft, using all types of guidance from the most primitive to the most sophisticated. These often have identical crew-related contributory causes to those found in much earlier accidents, such as descent below DH without visual reference, rendering this contention unproven.
It is similarly stated in some forums that PicMA is not relevant to current operations because crew training and in particular Crew Resource Management Training have improved sufficiently to render it redundant in improving cross-cockpit monitoring. The thrust of this argument is the PicMA concept pre-dated much human factors research which has led to a better understanding of workload distribution and interpersonal relationships in the cockpit. As a result CRM training is now a fundamental aspect of all pilot training, and is sufficiently effective to overcome such issues.
However, accidents and incidents in which poor preparation, inadequate resource management and ineffective cross-cockpit monitoring are major contributory causes continue to occur throughout the world, rendering this contention that CRM training has rendered procedural changes unnecessary to be unproven.
Other known arguments for maintaining the "status quo" of using only the traditional procedure centre on pilot satisfaction from flying an entire flight as the sole "pilot" from takeoff to touchdown, especially in good conditions. This is a psychological / emotional issue to be balanced against real safety concerns. For example, often events arise as a result of pilots' over-confidence that currently "benign" or good flight conditions will continue, leaving the crew vulnerable to and unprepared for subsequent adverse changes. There is no verifiable data to support arguments that maintaining the "status quo" would be safer than adopting PicMA in this regard.
Prior to WW2 there was little if any regulation of flight operations in poor weather, and anecdotal evidence exists of pilots improvising a version of the "monitored approach" procedure to help achieve landings in bad weather after unsuccessful traditional approaches. These informal practices became somewhat more widespread following WW2.
Concern about poor weather accidents led to initial research into the human factors underlying approach accidents. British European Airways, one of several airlines subsequently brought together to form British Airways (BAW), stated that "BEA's active interest .... began in 1948 .... when a serious accident involving one of our aircraft raised questions about the division of workload in the control cabin."
Although fundamental elements of workload distribution and cross-checking were addressed from the very first evaluations in the 1950s, the initial impetus for research into crew coordination procedures was the need for better regularity and enhanced safety in poor visibility. In the late 1940s extensive research into visual transition issues took place in the USA and in Europe, prior to presentation to ICAO in 1949.
The UK Blind Landing Experimental Unit, Bedford had developed the "Calvert" approach light system, which provided additional guidance compared to the systems being developed in the USA. During trials it was found that at the higher approach speeds associated with the new jet aircraft, every pilot on looking up from the instrument panel to the approach lights began to sink immediately below the glide path and became dangerously low before becoming aware of it ("Croydon to Concorde" by Capt R E Gillman, 1980, pp 129-131).
Although the Calvert system provided more guidance than the other systems, it was still inadequate for vertical guidance, particularly when the pilot was trying to adjust his visual focus while at the same time adapting to different cues. This and other research in the US, UK and Australia led to BEA's early formalisation of the "monitored approach" procedure. From the early 1960s this was used as the standard operating procedure for all approaches in British Airways' European operations, including sectors where the First Officer was the "pilot-in-charge" and making the landing.
By 1970 research by the United States Air Force Instrument Pilot Instructors School recognised the need to separate instrument flying tasks from acquisition of visual cues, and confirmed that at least three seconds exposure to cues is needed to make an assessment of flight path. It also confirmed that the vertical element is significantly more demanding. Similar work took place at research establishments in France.
In 1976 the US National Transportation Board carried out a Special Study of crew procedures in ILS accidents. While specific operators were not identified, this made reference to BEA's procedures in comparison to those traditionally used in the US carriers studied. While it did not specifically recommend that "monitored approach" be mandated in the US, it made recommendations for crew procedures that cannot realistically be achieved by traditional methods. These recommendations and are still largely unimplemented 40 years later. They are however fully met by the "monitored approach" method.
This research, and industry discussion resulted in the "monitored approach" procedure being adopted in US airlines such as Trans World Airlines , American Airlines and United Airlines in the 1970s, and often being mandated for operations in low visibility. This development was reflected in similar actions in other parts of the world.
In the 1970s issues of crew workload distribution became came increasingly discussed and the subject of "cockpit resource management" started being researched. Trials at NASA showed that crew decision-making is enhanced by the delegation of flying tasks to co-pilots, allowing commanders more capacity to manage and communicate. This since has become a basic aspect of "crew resource management". The reports did not specifically recommend adoption of "the monitored approach procedure", but such delegation is an integral aspect of it.
During the 1970s and 1980s a number of procedures trials took place during the development of Category 3 landing criteria in both Europe and the USA. These resulted in some detail modifications to crew procedures including changes to accommodate fully automatic landings, and the use of "alert heights" in place of Decision Heights. These were fully compatible with the "monitored approach" principle as well as "traditional" procedures.
In 1994 the NTSB conducted a further safety study of crew-related US accidents . Amongst other things, this study noted the particular problem of inadequate monitoring and challenging by First Officers, particularly in respect of Captains' tactical decisions. The reports did not specifically recommend adoption of "the monitored approach procedure", but elimination of this "authority gradient" is fundamental to the monitored approach procedure.
From 1997, following extensive internal discussion, British Airways (one of whose predecessor components was BEA referred to above) implemented the "monitored approach" procedure to be used on all approaches, including full role reversal at the Captain's discretion. (This type of implementation is referred to as Pilot in charge Monitored Approach on the website www.picma.org.uk).
In 2000, the NTSB published its report into the accident to a Korean Airlines B747 at Guam. Major contributory causes were workload distribution and ineffective monitoring by the First Officer and Flight Engineer. The report discussed the way that the "monitored approach" procedure mitigated this problem. The NTSB concluded that "monitored approaches decrease the workload of the flying pilot and increase flight crew interaction, especially when experienced captains monitor and prompt first officers during the execution of approaches." It recommended that the FAA investigate and determine the extent to which its use should be required for US carriers.
In 2004 the joint ICAO/Flight Safety Foundation/FAA "Controlled Flight Into Terrain" Training Aid was issued and contained recommendation 2.1.6 that "operators consider adopting a monitored approach procedure during approaches and missed approaches conducted in these conditions".
In 2006, the Canadian aviation authority Transport Canada published Advisory Circulars 237 and 239 . AC 239 describes a "monitored approach" procedure and indicates its advantages in poor visibility, while 237 authorises operators that use such procedures to operate to lower visibility limits than those that do not.
In 2009 the NTSB noted in respect of its 2000 recommendation that the although FAA had not required operators to modify their procedures, it "has generally found that carriers are increasingly adopting and using the monitored approach technique." However, a reverse trend has also been identified particularly in North America, apparently as a result of some carriers that had adopted monitored approach procedures being merged with others which did not. In those cases it appears that the resulting carrier has for various reasons elected to standardise on continuing to use traditional PF/PM procedures.
This answer is largely sourced from a peer-reviewed article on the Skybrary website by the same author. Detailed rationale and access to the research material on this subject has been collated on a website at http://www.picma.org.uk, where the writer's qualifications can also be viewed.