Questions tagged [separation]

Questions regarding the distance separating aircraft during flight.

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-1 votes
1 answer
45 views

Does the pressure recovery on an airfoil cause separation more with turbulent BL’s?

If you have a turbulent boundary layer going through pressure recovery on an airfoil, why is it more likely to separate than a laminar boundary layer? From my research/intuition I think turbulent ...
0 votes
2 answers
113 views

Is there any instrument on board to assure horizontal collision avoidance?

I know that TCAS are used to get 'Traffic Alerts' as well as 'Resolution Advisories'. But an RA seems to only provide instructions to avoid vertical collisions. How about the horizontal separation, ...
0 votes
0 answers
81 views

Does airbrake reduce or increase static pressure downstream of it?

When airbrake is down, flow is fully attached on upper surface, when airbrake lift up flow separate. Is static pressure at point 2 and 3 now lower or higher compare when airbrake is down? CFD video ...
6 votes
2 answers
398 views

How do IFR flights in IMC in Class G airspace not collide?

According to Wikipedia, in Class G airspace, "Operations may be conducted under IFR or VFR. ATC has no authority but VFR minimums are to be known by pilots. Traffic Information may be given as ...
7 votes
2 answers
895 views

What are the separation requirements on the ground?

What are the FAA regulations for aircraft separation on the ground, outside of active runways?
3 votes
3 answers
2k views

How exactly do ICAO's VOR-based minimum separation standards work?

This question is aimed at Air Traffic Controllers who are familiar with ICAO Separation minima. DOC 4444 states the following: Lateral separation between two aircraft exists when: VOR: both ...
7 votes
4 answers
2k views

How safe is IFR in class E?

In class D and E airspace, there is no separation between IFR and VFR traffic. However, most airspace in the United States below 18,500 feet MSL is class E airspace, which is exactly where non-...
3 votes
1 answer
929 views

Is the published recommendation on when to turn crosswind dangerous?

Citing the FAA from Airplane Flying Handbook On the departure leg after takeoff, the pilot should continue climbing straight ahead and, if remaining in the traffic pattern, commence a turn to the ...
2 votes
1 answer
520 views

Why does DME colocated with VOR require more separation?

In earlier versions of ICAO Doc 4444 (Amendment 9 and earlier), two aircraft were deemed to be laterally separated if they were departing a VOR on radials which diverged by at least 15 degrees and if ...
0 votes
2 answers
897 views

What is the vertical separation minima between IFR and VFR?

ICAO Doc 4444, 5.3.2 says The vertical separation minimum (VSM) shall be: a) a nominal 300 m (1 000 ft) below FL 290 and a nominal 600 m (2 000 ft) at or above this level, except as provided for in b)...
11 votes
3 answers
2k views

How does a TCAS system avoid unnecessary (RAs) resolution advisories when aircraft are operating on separate closely spaced parallel runways?

How does a TCAS system avoid unnecessary (RAs) resolution advisories when aircraft are operating on separate closely spaced parallel runways (e.g. 2500 feet or less separation between rwy centerlines)....
4 votes
2 answers
3k views

Who is responsible for aircraft separation in IFR (limited/no visibility)?

I was reading how-much-is-the-minimum-safe-distance-between-two-planes-in-flight and realized part of it confused me (or maybe I'm just tired.) In a low- or no-visibility environment (i.e. under IFR ...
1 vote
3 answers
414 views

Are mode C altitude returns valid for aircraft separation?

According to FAA JO 7110.65 5-12-8 'Validation of MODE C READOUT', Mode C is valid if there is less than 300 feet deviation from the pilot reported altitude. If ATC instruct 'A' aircraft to maintain 5,...
3 votes
2 answers
200 views

Is there any current and/or upcoming technology that alerts Air Traffic Controllers in case of loss of aircraft separation?

Currently doing an assignment and it to analyse an accident where older atc systems could have been at fault. In 1995 there was an incident where two aircraft came closer than the then current ...
1 vote
2 answers
298 views

During VMC conditions in terminal airspace (class B), does the pilots have to strictly follow separation standards issued by ATC?

Is it common for pilots to breach separation standards in terminal airspace while the conditions are VMC? I'm interested primarily in commercial aircraft that have scheduled operations in major ...
9 votes
3 answers
2k views

How does ATC handle changing QNH/altimeter values?

Obviously for aircraft arriving to or departing from an airport/airspace (as relevant), they listen to the ATIS and/or are given the QNH. But what happens if that pressure changes? Even a fairly ...
3 votes
2 answers
332 views

Will there be dynamic or variable separation minima in future?

In the future, is it possible to apply in the same airspace different separations between pairs of aircraft? Depending on the relative speed, navigation capacity of the aircraft, intersection geometry,...
3 votes
0 answers
78 views

How did lateral and longitudinal separation minima evolve?

What is the evolution in time of lateral and longitudinal separation minima?
0 votes
2 answers
261 views

How to find runway Centerline spacing on airport diagrams?

I know that airport diagrams show the exact position of airport runways in DMS (degrees, minutes, seconds) and therefore could use trigonometry to find how far apart runway centerlines are from ...
41 votes
5 answers
98k views

How much is the minimum safe distance between two planes in-flight?

According to FAA regulations, how far should a commercial jet be away from another plane in-flight? How about military planes? They get really close when in formations... Is there a minimum distance?
0 votes
1 answer
180 views

Which avoidance maneuver is best when seeing crossing traffic on approach to a runway?

Let us say I am in final landing and I saw another aircraft is crossing the runway while I am still in air, should go around be my best choice? If I touched down and then I saw the traffic, how ...
7 votes
2 answers
751 views

Are there conventions on which side to travel on Victor airways - USA?

I'm a low-time VFR pilot (100hrs) in the United States. I have not yet started IFR training (other than XC time building). I understand the purposes and reasons why the Victor airways exist. I also ...
3 votes
3 answers
614 views

How to determine the traffic avoidance manuver?

Scenario A: I started the takeoff roll and then noticed another aircraft is crossing the runway in front of me, how could I determine what is the best avoidance maneuver, like full braking to abort ...
11 votes
6 answers
5k views

What will be the immediate action by the pilot and ATC if any plane blocks the runway while landing?

Suppose, if the Airport has only one runway and one plane is trying to take off at the end of the runway and other plane trying to land from the other end of the runway. Due to any reason if the ...
3 votes
0 answers
95 views

What is the FAA regulation for the 3 mile / 1,000' separation for a commercial airliner? [duplicate]

I need help finding the Number/Citation for the FAA regulation/order that states commercial airliner separation should usually be at least 3 miles laterally, or 1,000 feet vertically. I cannot find ...
5 votes
1 answer
409 views

Is separation provided in class F airspace?

According to the Wikipedia page on different airspace classes, separation is provided for IFR/SVFR to other IFR/SVFR in class F airspace. In ICAO Annex 11 from 2018 (p.36 in the pdf file), I can't ...
3 votes
1 answer
188 views

What would be a safe minimum vertical separation distance between passenger-carrying multicopter aircraft?

There is increasing talk about employing passenger-carrying multicopters ("taxi drones") to extend urban mobility into the third dimension. These aircraft will have MTOMs in the range of several ...
11 votes
5 answers
4k views

How is radar separation assured between primary and secondary targets?

Air traffic control radars come in two flavours, with most ATC centers using both and displaying the output of both on a single screen: Primary surveillance radar (PSR) is a true radar system, which ...
1 vote
1 answer
355 views

How does the ICAO VOR separation apply to reciprocal radials?

If two aircraft are on VOR radials that are apart by 15 degrees or more and one aircraft is at least 15 DME out, they are considered laterally separate. I read this rule in ICAO documents but my ...
7 votes
2 answers
795 views

What does "leave clear on its left" mean in UK regulations relating to collision avoidance on non-runway landings?

This doesn't seem to be plain English, could someone explain this with a simple example for me please? I'm not sure what 'Leave clear on it's left' means, and it's not clear whether the subject of the ...
6 votes
1 answer
711 views

What does "zero offset between two waypoints" mean in ICAO Doc 4444?

My question is with reference to the GNSS based separation specified in ICAO Doc 4444. Could someone explain the significance/meaning of the condition "zero offset between two waypoints" criteria? if ...
6 votes
2 answers
1k views

Why do planes above FL290 need more vertical spacing?

At altitudes no higher than 29,000 feet, planes need only 1,000 feet of vertical separation. However, planes over FL290 need twice that, i.e. they need 2,000 feet of vertical spacing between them and ...
6 votes
3 answers
761 views

What vertical separation is required in a holding stack to avoid wake turbulence?

Sometimes in my free time I play Endless ATC, a game where one acts as the approach and departure controller. In the game (as in real life) the controller is forced to put planes in a holding stack, ...
6 votes
4 answers
1k views

Why do heavy departures wait 5-10 minutes on the runway at ZRH?

I'm frequently travelling to Zürich for business and I usually make my schedule so that I have at least an hour to do some planespotting and photographing at the ZRH airport. Whenever I came to the ...
3 votes
2 answers
1k views

Why are both ATC and TCAS tasked to prevent collisions although TCAS takes precedence anyway?

« The primary purpose of ATC worldwide is to prevent collisions [...] Many aircraft also have collision avoidance systems, which provide additional safety by warning pilots when other aircraft get ...
3 votes
2 answers
746 views

Is the Tower (Local) Controller responsible for "separating" VFR traffic in the pattern in the U.S. in Class D airspace?

For example, in U.S. Class D airspace, if an inbound aircraft operating VFR is instructed by the Control Tower to "enter left downwind for runway 18, report entering downwind," is the controller ...
11 votes
1 answer
1k views

Vertical and horizontal separation between cruising and climbing aircraft

I was recently a passenger on a commercial aircraft at cruise altitude when I noticed another aircraft just reaching its cruising altitude while crossing our flightpath from below, at what looked like ...
5 votes
1 answer
714 views

Is true altitude vertical separation between airplanes dependent on temperature?

Does the "true" altitude vertical separation between airplanes (using the same altimeter setting) vary as the temperature changes? ( I fully realize that the "true" altitude of both airplanes is ...
5 votes
1 answer
421 views

How close is this Su-27 to the aircraft recording the pass?

There is footage of an intercept of a US Nay recon aircraft being intercepted by a Russian Su-27: (still from the BBC video article, who look like they got it from the US Navy directly) which was ...
3 votes
0 answers
166 views

Diversions because of fog: What are the reasons?

It's fog season again around my local airport MUC (EDDM), and I have noticed a number of diversions recently. Some planes were holding a bit before attempting to land, performed a go around and then ...
5 votes
2 answers
594 views

Can RVSM safely be further reduced?

Since the world population shows no signs of slowing down its rapid increase, it's pretty safe to say that means we can only expect more concurrent flights as time moves forward. Is it physically ...
1 vote
0 answers
83 views

What is the legal definition of separation as it relates to ATC? [duplicate]

ATC provides "separation" for all aircraft in class bravo airspace. What is the legal definition of separation? Is it the same or different than the see-and-avoid rule (FAR Part 91.113(b)) where all ...
20 votes
2 answers
12k views

What are the most efficient layouts of multiple runways?

Many airports have more than one runway. How should runways be built in order to achieve maximum usage and minimum delays? Many major airports have most, if not all, parallel runways. Examples ...
6 votes
1 answer
652 views

How is separation managed when there are only two parallel runways in a very busy airport?

In the world's busiest airports, how is separation managed between departures and arrivals when there are only two parallel runways like in London Heathrow. What is the minimum safe separation?
1 vote
4 answers
229 views

How to make ourselves more visible to other aircraft?

What are the best practices in air to help others see our aircraft?
18 votes
1 answer
11k views

How does vertical separation work above FL400?

The information mentioned in "Jeppesen Airway Manual" is that after FL400, fight levels are FL430, FL470, FL510 for the 'even' FL's column. Normally, I would expect every level divided by a thousand ...
48 votes
6 answers
36k views

How close can planes fly to each other over the ocean?

While on a recent Air Transat flight from Toronto Pearson to London Gatwick, several hours into the flight and over the Atlantic Ocean, my daughter and I noticed a plane behind ours to the left, ...
21 votes
2 answers
2k views

What information does a pilot have about aircraft operating on an intersecting runway?

This incident at O'Hare from July 2006 made me wonder what information is available to a pilot (specifically, in an airliner) regarding aircraft that are using an intersecting runway. In this ...
10 votes
2 answers
4k views

How do ATC radars know where to position a primary target?

Primary target: An aircraft not reporting mode-C, the only thing the controller has is the return on the radar. When a controller reports a primary target as traffic to other aircraft, the controller ...
1 vote
1 answer
566 views

What is the minimum separation for aircraft operating on or intersecting the same runway?

How capturing of this photo was ever possible: (photo courtesy of jetphotos.com) Shouldn't there be a bigger time / distance separation of three aircrafts using, operating or intersecting the same ...