# Would turbulence created by two jumbos less than 100ft apart cause both of them to crash?

In a scene from Spider-Man 2 (2014), which you can see in this video, two jumbos almost collided. At the last possible moment, the pilots were able to save their planes, but both planes came to within 100 feet apart from each other (I guessed the distance). Both planes survived.

I wonder in real life with real science and no Hollywood involvement, could any plane survive this close encounter with another jet?

• tcas would never let them come so close. – anshabhi Aug 29 '15 at 4:55
• @anshabhi TCAS is not magic. Aircraft equipped with TCAS have come within 100 feet, and closer (metal-on-metal close in some cases). – voretaq7 Aug 29 '15 at 5:43
• @voretaq7 , isn't turbulence causing serious problem for jets that close? – TBBT Aug 29 '15 at 7:01
• For what it's worth, it's not two jumbos. It's a 747 and a narrow-body jet. – David Richerby Aug 29 '15 at 17:52

The probability of two jets surviving such a close encounter are extremely remote.

Setting aside the fact that it is difficult to imagine two aircraft flying in the same altitude in opposite directions (commercial aircraft are separated by 3 miles laterally and 1000 ft. vertically) ,if the scenario unfolds as in the movie and the horizontal separation between the aircraft on approach is as shown, the pilots would not have time to react and take the necessary evasive actions.

Assuming that the jets are cruising towards each other at 900 kmph, the combined speed is around 1800 kmph, or half a kilometer per second.

If the TCAS is not working and the aircraft come within five km (the distance in the video is considerably lower, less than a km) of each other, the pilots have less than 10 seconds to get out of each other's way.

The civil aircrafts are not designed for such rapid roll rates. The inertia of the aircraft (especially the 747) will limit it.

Another thing to note is that the modern flight control systems will not allow airline pilots to carry the maneuvers shown in the flight. The pilot can override the Flight control Computer.However,in this case, they would not have time to react.

If by some miracle the aircrafts cross each other, they will fly right into the other aircraft's wake turbulence, which will have disastrous consequences, especially for the smaller aircraft.

Sources: airpower.maxwell.af

In case of small aircraft flying behind a heavy jet, FAA regulations require a minimum separation of 5 miles, lesser than which the effect of the wake turbulence (wingtip vortices) can have serious consequences.

Source: Aeronautical Information Manual

FAA conducted a test on the effects of wake turbulence by flying a 737 behind a 727, which shows the loss of control associated with flying in the wake of another aircraft.

Once (if) the aircraft pass each other, they should be brought to level flight as quickly as possible (whether it is possible or not is another question) to prevent stall. In this critical juncture, if the aircraft wings encounter wake turbulence, the control of the aircraft will be loss, resulting in stall.

Finally, in case two aircraft do approach each other in the same altitude in opposite directions, there are laid down procedures to follow. None of them involve the stunt shown in the movie.

When two aircraft are flying head on, each must move to their right.

Source: planefinder.net

If two aircraft are at the same height and on converging courses, the aircraft with the other on its starboard side has to give way.

Source: planefinder.net

• Great explanation. I understand it now. – TBBT Aug 30 '15 at 5:08
• In a close collision situation (where the pilots have not seen each other until they are nearly colliding, it may not be possible to follow these rules, because banking takes time and the upturned wing might hit the other aircraft. Pilots in this situation might consider one will go up the other will go down, although there are no rules for this, and because going down is easier (and faster) both might decide to go down. This is why I would always try to fly at a different altitude to other traffic in the close vicinity where possible. – Philip Johnson Aug 30 '15 at 6:24
• "commercial aircraft are separated by 3 miles laterally and 1000 ft. vertically" - What's the logic behind this? and is 1000ft safe, because we hear frequently that planes suddenly lose altitude due to updraft / downdraft etc.. – Firee Aug 31 '15 at 13:41

Wake turbulence is a serious problem if flying too close to another aircraft, for example if a light aircraft follows a larger aircraft, the sheer amount of air and wind speeds involved could cause a loss of control and possible subsequent damage to the aircraft if not rated for aerobatics (or if close to the ground). You have to stay quite a long way behind a larger aircraft when approaching to land to be sure of not encountering it.

However if encountering wake turbulence from an aircraft of a similar size, while you would most definitely feel it, I don't think it would cause a loss of control.

Even so, when flying in formation aircraft stay away from the others wake turbulence because although I don't think it would cause them to crash it would be uncomfortable and the formation wouldn't look smooth if at an airshow for example.

To answer the other part of your question - would it affect the aircraft in front? Only if the aircraft behind lost control and hit it, as was thought to happen to Joe Walker who was flying a F104 and hit the aircraft he was chasing causing both to go down

, it was suspected that the F104 was caught wake turbulence from the large aircraft.

• This answer doesn't have very much to do with the question. The situation in the video does not involve one plane flying behind another; rather, it shows then narrowly avoiding a head-on collision. – David Richerby Aug 29 '15 at 17:54
• It wasn't head on, the F104 was flying on the wing of the XB-70 in the same direction and the F104 got caught in the XB-70's wingtip vortice (part of the wake turbulence) and got carried along by that vortice until it hit the top of the XB-70. Sorry you don't think it was relevant, I was only trying to help, I used it to demonstrate that while the F104 was washed around like being inside a washing machine, the larger aircraft didn't move at all, until later in the accident sequence when control was lost due to having no fins or rudders. – Philip Johnson Aug 30 '15 at 6:14
• I'm sorry I haven't seen the film. If it was head on in the film, then wake turbulence would have no affect. Whether the planes survived or not would simply depend on the amount of G's pulled to avoid each other.As a pilot I took the word Turbulence in the original question to mean wake turbulence, because there isn't really any other kind created by an aircraft that could affect another aircraft. – Philip Johnson Aug 30 '15 at 6:18
• Sorry, I was unclear. I meant that the video in the question is a head-on situation. – David Richerby Aug 30 '15 at 9:04