The "Window" of Opportunity

[ImageGear]

Creeping out of LHR on the SID from 27R to the north after Burnham about 7000' not apparently climbing and virtually no viz.
Sat in seat 4A talking to a lady in 4C.
Aircraft banks gently to port perhaps 20 degrees as if crossing an intersection.
While rolling out, seconds later, another very large (VERY LARGE) aircraft flashes past the window at 4F going in the opposite direction. (Possibly widebody but so fast (milliseconds) could not even tell but remembered seeing a string of windows).
Now the field of view from the opposite side of the cabin is small so
co-altitude, and almost nose to nose. Surely the TCAS would have been shouting, not to mention London Control.
I am reluctant to mention it because of the scathing comments about spotters and distances, heights and speeds being easily mistaken on these threads.
However, the "Window" of opportunity was very small.
Comments ?
Imagegear.

[Getoutofmygalley]

You say you were at about 7000 feet but virtually no viz, so you most probably were mistaken on the height.

If the aircraft was still banking when you saw the other aircraft, you would have been looking at an aircraft that was actually considerably lower than yourself, but owing to the bank angle it would appear to be at almost the same height.

Someone more experienced can come along and comment further, but that is what I would put my money on :)

[AltFlaps]

The most likely reason that you were not climbing was because there was probably an aircraft level 1000' above you (which is minimum separation). This would make perfect sense, in that your aircraft had to wait until it was cleared to climb.

You said a left turn, and you were sitting on the left. You also said that you saw the other aircraft from 4F (I assume the right window) as you were in the turn to the left.

That would mean that anything you were seeing out of the right window would have been higher that your level, and therefore probably the aircraft that was blocking your climb ....

This is all guesswork of course, and as has been said on lots of occassions, there are systems and procedures in place ...etc...

If there was a threat, then TCAS should has provided the crew with a resolution manoeuver. If for some reason the aircraft was not sqwuaking or had no transonder, then you can be sure that (especially if it was a VERY LARGE aircraft) that ATC would have been aware of it in the London TMA (even if only from a primary radar return).

There are no conspiracies going on, just another busy departure in the London TMA :ok:

[ImageGear]

Your comments about the turn would be valid if we had not already virtually rolled out. (Vertical viz was good so I could see the ground, horizontal was poor)
However as I said, when I looked across at the opposite window, I could only see the aircraft's windows, I could not even see the fuselage completely.

If it was 1000' away I would easily have seen the whole jet or more than likely not, since the horizontal viz was so bad.

PS I occasionally get to pole so I know roughly what 1000' looks like.

Still might have been a reflection on the clouds - might be my mistake.

Imagegear

[AltFlaps]

Maybe it was an Airmiss then !
Why don't you ask the airline to shed some light on it ? If it did happen, there WILL be paper work on it ...

[BOBBLEHAT]

You were almost certainly on a WOBUN SID from Heathrow and depending on the Atmoshperic pressure you would probably have been at 6000ft perhaps climbed to FL70 or FL80. There are two main conflictions in that area. 1. The Bovingdon Hold 1000ft above you or 2. A Luton CPT departure which would probably be 1000ft below you. Sometimes you will be sandwiched by both.

I very much doubt there is anything dangerous or untoward about your experience. It happens about 40 times a day and we're all very careful! 1000ft vertical separation isn't much and can look even less to the untrained eye.

Mistakes do happen though...................................

[ImageGear]

Yes, I know about the Wobun SID, Bovingdon and the Luton departure.

I think this is done to death now but next time the aircraft is on stand sit in
4A and take a look through the window at 4F at the aircraft in the next stand. (You will be level) Yup, you can't even see all of the fuselage.

That sucker was very, very close.

Clearing out to the NorthEast.

Imagegear.