6
$\begingroup$

Flying close to the ground is really dangerous and yet needed to land and take off. ILS is designed to keep the adequate trajectory close to the ground with (almost) no visibility. Is there a similar system for take off, e.i. a system helping pilots to maintain the adequate trajectory near the ground with almost no visibility at take off?

$\endgroup$
  • 1
    $\begingroup$ Yes, SIDs $\endgroup$ – Simon Oct 15 '15 at 11:14
  • 2
    $\begingroup$ SIDs should be compared to STARs. There is nothing compared to ILS for takeoff. $\endgroup$ – kevin Oct 15 '15 at 15:22
  • 1
    $\begingroup$ The closest thing to an instrument take-off system is a "takeoff guidance system", now simply referred to as a HUD by the FAA. For more information on how that works, see this question. $\endgroup$ – Lnafziger Oct 18 '15 at 14:26
6
$\begingroup$

While there is not a specific physical system dedicated to instrument departures per se, there are procedures that rely upon instrument flight rules (IFR) navigation equipment that ensure obstacle clearance when departing from an airport in instrument meteorological conditions (IMC).

From the Aeronautical Information Manual 5-2-8.

Instrument departure procedures are preplanned instrument flight rule (IFR) procedures which provide obstruction clearance from the terminal area to the appropriate en route structure. There are two types of DPs, Obstacle Departure Procedures (ODPs), printed either textually or graphically, and Standard Instrument Departures (SIDs), always printed graphically. All DPs, either textual or graphic may be designed using either conventional or RNAV criteria. RNAV procedures will have RNAV printed in the title, e.g., SHEAD TWO DEPARTURE (RNAV). ODPs provide obstruction clearance via the least onerous route from the terminal area to the appropriate en route structure. ODPs are recommended for obstruction clearance and may be flown without ATC clearance unless an alternate departure procedure (SID or radar vector) has been specifically assigned by ATC. Graphic ODPs will have (OBSTACLE) printed in the procedure title, e.g., GEYSR THREE DEPARTURE (OBSTACLE), or, CROWN ONE DEPARTURE (RNAV) (OBSTACLE). Standard Instrument Departures are air traffic control (ATC) procedures printed for pilot/controller use in graphic form to provide obstruction clearance and a transition from the terminal area to the appropriate en route structure. SIDs are primarily designed for system enhancement and to reduce pilot/controller workload. ATC clearance must be received prior to flying a SID. All DPs provide the pilot with a way to depart the airport and transition to the en route structure safely. Pilots operating under 14 CFR Part 91 are strongly encouraged to file and fly a DP at night, during marginal Visual Meteorological Conditions (VMC) and Instrument Meteorological Conditions (IMC), when one is available. The following paragraphs will provide an overview of the DP program, why DPs are developed, what criteria are used, where to find them, how they are to be flown, and finally pilot and ATC responsibilities.

There are many details involved in actually using these procedures to make safe departures in IMC. The Instrument Procedures Handbook Chapter 1 is an excellent resource for pilots who want to review these procedures, what they provide and how to use them correctly.

Here is an example of an ODP from my home airport, KCRG. There are some very tall towers less than 10 nautical miles from the airport. They are enormous and easy to avoid under visual conditions, but when IMC prevails these procedures are absolutely life-saving with such large obstructions nearby. They are taken from this takeoff minimums document.

ODP

Here is an example of a SID. These are always graphically depicted and will usually be found at larger airports. Here are pages 1 and 2 of the full SID.

SID

$\endgroup$
4
$\begingroup$

As Simon mentions, there are the Standard Instrument Departure procedures. They need not be that precise. Remember that in landing, 50 ft verctial or in lateral (left/right) deviation can easily lead to a disaster. This is not true for departure once you are airborne; 50 ft make no difference, the separation of the used routes is much much larger. Before you are airborne, you see the runway below you, and you just double-check it's the correct runway and you've got enough length of it; but neither of these directly depends on the visual.

Last but not least, if the runway has an ILS in your direction or the opposite one, you can use its horizontal part to navigate yourself straight out of the airport; you can't use the vertical part of course, since the desired climb angle rarely coincides with the glide slope.

$\endgroup$
  • $\begingroup$ Using the localizer for runway alignment, as in a low-visibility takeoff using a HUD, you actually use the LOC for the runway you're using, rather than the opposite direction. Typically, only 1 or the other is turned on at a time. $\endgroup$ – Ralph J Oct 15 '15 at 14:30
  • 3
    $\begingroup$ Well, 50 (especially altitude) can make a difference on departure if your roll used most of the runway and there are obstacles that you need to climb over past the end of the runway. It doesn't make so much difference once you're above ground obstacles, though. $\endgroup$ – reirab Oct 15 '15 at 14:58

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.