88

It was only very slightly higher than our plane by mere meters. You think you saw a plane at the exact same vertical level as yours, when in fact it was at least 300 metres (1000 feet) above or below your level. It can be very hard to judge differences in level for the untrained eye, especially over the ocean and at night when there is nothing to reference ...


70

This is an excellent question, and helps illuminate several important aspects of the way perception works in aviation. But first... Any near-miss or other air-proximity incident would have been reported If there had been any risk of a collision, it would have been reported, unless somehow (and this is astoundingly unlikely) the entire flight crew of both ...


53

The question specifically asks about FAA regulations, so I will try to provide specific citations. Summary For a commercial airliner (as the question asked), separation will usually be at least 3 miles laterally, or 1,000 feet vertically. In the enroute environment -- at higher operating speeds above 10,000 feet and based on the type of Radar and distance ...


25

You didn't mention which country or jurisdiction you're asking about, but in the US 14 CFR 91.113(b) says: When weather conditions permit, regardless of whether an operation is conducted under instrument flight rules or visual flight rules, vigilance shall be maintained by each person operating an aircraft so as to see and avoid other aircraft I ...


25

ATC will tell the landing plane to go-around. The pilot will then execute the go-around by flying the missed approach procedure as published in the airport charts. Go-arounds happen daily and are pretty much a routine action. In any case, if the landing pilot feels that the runway is not safe for landing, he can decide to go-around by himself without ATC ...


21

The things you mention would matter, if you wanted to know the distance to 6 or more significant digits. But ATC does not need that precision. They need to be able to tell whether it's 4 nmi (too close), 5 nmi (still sufficient, but getting in trouble) or 10 nmi (no worry, but should not be heading directly towards each other). That is one significant digit. ...


19

For flights above FL410, 2000 feet of separation is used. Which makes all flight levels odd numbered, →410, ←430, →450, ←470, →490, ←510, ... So for each direction as indicated above by arrows, it'll be 4000 feet. The 2000 feet separation is because the higher up you go the less accurate an altimeter becomes, so it's for safe separation. Even/odd is just ...


16

A "small" transatlantic plane probably isn't very small -- it was probably further away than you think. Compare these silhouettes (can't embed due to image rights, also can't vouch for accuracy): 737 (31m) 757 (47m) 767 (49--61m) 777 (64--74m) (Just look at the first and last for a quick indication of what I mean) In brackets are the lengths (ranges ...


15

This is somewhat speculation, but here's what I think happened: You were flying at around 35,000 feet, in RSVSM airspace. The fighter jet was correctly on track 1000 feet below you. Without any other guides of distance, you tried to judge its distance by apparent size compared to real size. You might have underestimated the size of a fighter jet; they're ...


15

I think you may have answered your own question note the use of the word OR To my understanding, aircraft at these altitudes should always have a separation of least 1000 ft or 5 nm. If you take a look at your data the aircraft are always separated by 1000 feet OR 5nm. The singular exception to this is when you have the separation quoted at 4.81 miles ...


14

In order to increase the number of operations that can be handled at a runway, you want them configured so as to allow "simultaneous independent approaches," which means that the 2 (or more) runways can be operational without the need to coordinate between them. The biggest factor is the distance between the two runways. The greater the distance between ...


14

As the question mentions, good situational awareness is an excellent safety tool. ATC is responsible for runway separation at towered airports, but pilots can play an important part of backup in the case of a human mistake. The United pilots may or may not have been able to see the Atlas 747 on TCAS, as the terminal building that obstructed their view could ...


14

Pilots are allowed to fly as close as they want to each other as long as all parties agree to it and feel safe doing so. Air Traffic Control cannot guarantee separation for planes in formation flight,So this will only be done under VFR and in VMC, where pilots can maintain visual separation from each other. Many stunt fliers are civilian pilots and will ...


13

First of all, there is no such thing as a stall speed, but that is a topic of its own. The ATC system has numerous ways of dealing with keeping aircraft separated, even at high levels. Let me try to summarize some of the most important ones, starting with the planning that happens when planes are still at the ground at their departure airport, working our ...


12

You already have a good answer on separation specifically, but it's worth noting that there are a few general rules about formation flights in 14 CFR 91: The most specific formation rules are in 91.111: §91.111 Operating near other aircraft. (a) No person may operate an aircraft so close to another aircraft as to create a collision hazard. (...


12

How close can planes fly to each other over the ocean? The visual perspective from the cockpit or passenger window often makes another airplane look much closer than it actually is. As previously stated, the minimum vertical separation during enroute flight is 1000 feet. But, as I mention, when aircraft are somewhat close laterally, but separated ...


11

In the US, ATC simply broadcasts a notification on whatever frequency is needed. For the terminal environment, section 2-9-2 of the ATC orders says: Broadcast on all appropriate frequencies to advise aircraft of a change in the ATIS code/message. The phraseology is usually something like this: Attention all aircraft, Bowman information Kilo is now ...


11

Primary radar, even modern digital systems, do not give any possibility to the controller to determine altitude. The digital system has that capability, but civil ATC does not. In primary radar displays usually just the azimuth and range are plotted. So an aircraft at 15.000 ft 9.5 NM away will be plotted on 10 NM distance, just like an aircraft at 0 ft ...


11

While ATC's primary goal is to prevent collisions, it is also responsible for the efficient movement of aircraft through the airspace. That requires a strategic approach to managing air traffic to get aircraft from point A to point B safely and in a timely manner. The primary tool ATC uses is the flight clearance. If air crews follow their clearances ...


9

As with any flight, "It's as safe as you make it". The vast majority of the General Aviation fleet (piston singles) don't even have an autopilot, and the ones that do may only be single-axis units (wing levelers), so the pilot has to have some level of attention on flying the airplane. If we assume these are the folks flying around VFR we can also generally ...


9

ATC assures separation... This is a pretty critical misconception. ATC does not necessarily provide separation, just because you are flying IFR. Let's do a quick recap of the different airspace classes. In class D, ATC will provide separation between two IFR flights, but will not separate VFR flights. All flights are provided with traffic information, and ...


8

you have 3 separations for commercial flights vertical separation: two aircrafts flying in the same direction will be separated by 2 flight levels (FLs), equivalent to 2000 ft. The intermediate FL is occupied by planes flying in the opposite direction. Each aircraft has thus 500 ft above and below the assigned altitude of free airspace. lateral separation: ...


8

Something to note here would be that modern aircraft contain a Traffic collision avoidance system (TCAS). So pilots in both aircraft would have been notified that they were on a collision and one would be told to change altitude. The system is so reliable that in the event TCAS and ATC orders conflict, TCAS is to be obeyed (due to a midair collision over ...


8

With two runways, usually, one is dedicated to arrivals, and the other is dedicated to departures. That's the simplest way to handle separation -- only in-trail separation is involved. That's usually the way traffic is managed at Heathrow (LHR) and Dubai (DXB), two of the world's busiest two-parallel-runway airports. At Heathrow, when in a westward flow (...


8

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 That would never happen. Planes are under ATC control from the moment they start their engines until the moment thay shut down their engines at the destination. (This is a simplification, but for the context of this question it makes ...


7

Radar controllers take wind into consideration when issuing headings - "Fly heading one six zero". Issuing a track would not be practical. This puts the burden of figuring out what course to fly on the pilot. Not all aircraft have a glass cockpit or instrumentation necessary to easily, quickly, and accurately compute a heading to fly to stay on course. The ...


7

It is a bit of a grey area and the answers you'll get will depend also on which field of expertise you are in. I am involved in developing and standardising ATC surveillance systems, here's my take on it. Loss of separation is the simplest definition of the two and it has regulatory consequences. But even that one is not black and white. How do you ...


7

ATC is always responsible for IFR-IFR separation, regardless of weather conditions. That is their primary mandate, and all other services are provided on a workload-permitting basis. In visual meteorological conditions, pilots of IFR aircraft are also responsible for seeing and avoiding other aircraft. But for IFR traffic of course this is not always ...


7

The STCA (Short Term Conflict Alert) or pre-alert settings depend on the radar client in use and the ACC's or ARTCC's own standard operation procedures. Some ATC systems give a warning before a loss of separation can occur if criteria are met, informing the controller of a possible conflict. Factors can be clearing aircraft on the same altitude / flight ...


7

Specifically, do airline pilots have any additional means for determining the position of other aircraft on intersecting runways aside from relying on ATC, listening to the Tower frequency, and looking out the window? Basically the answer is no. The only thing that could have been of help is TCAS, however: Aircraft on the ground are not visible on ...


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