wrp96

Welcome to FT. Sorry it took you going through an experience like this to join us.

Starship73

�3g� means the aircraft accelerated downwards (or �fell�) at three times the normal rate of gravity, ie 9.81x3 metres per second per second

bonnie111

I was on the flight. The crew were collecting meals at the time and thankfully all passengers had seat belts on or it would have been much higher casualties. It was very scary but the staff did an amazing job. It happened so fast the staff just had no time to get to their seats. I never fully appreciated the difference of wearing a seat belt until this.

EsherFlyer

1000'/s is rather fast - about 700mph average. It would mean starting at 0'/s (level flight) and ending up with something much higher. A bit like jumping in a flowing river and being whisked from zero to speed of river very rapidly. Something doesn't really add up in the numbers. 3G would go from zero to about 100'/s (65mph) in one second, with a fall of about 50'. That sounds quite plausible if there is a downpush effect, and enough to cause significant injury when coming back to zero very rapidly.

I'd understood that turbulence was largely due to "holes in the air" where there was a sudden change to the density or velocity of speed over the wings leading to change in lift so that acceleration effects would be up to 1G (just like my step off of platform mentioned above). Is there also an effect where the aircraft may find itself being actively pushed vertically?

Waterhorse

Clear air and convective turbulence are different in more ways than just the obvious. Clear air turbulence tends to be associated with lateral shear in the air- ie the air behaves more like a river with one parcel of air speeding past another at the same level. Like a river this causes eddies and is normally more violent on the colder side ie to the north or left of flow in the northern hemisphere. It is difficult to predict and doesn�t show on radar, there is very little vertical extent to it, which is why planes will climb or descend to another level when there is clear air turbulence - it is very often associated with jet stream activity.

Convective turbulence is associated with clouds or airflows near clouds. This can have an extensive and large vertical component. There can be significant air movement at some distance from the clouds, but it is not true clear air turbulence as the source can be seen. In the tropics and indeed with any large cumulo-nimbus cloud we avoid them by at least 20 miles at altitude to avoid (as much as possible) the high energy air flows around them.

To get significant vertical shear away from a cloud is highly unusual.

The 1000ft in a second smacks a little of shock and startle to me. I wasn�t there but I doubt it was quite as severe as that and recollection of times can easily be distorted through that lens. It could also have been that the speed loss required a 1000ft descent to recover.

1000ft in 1 sec would mean the aircraft was physically accelerated downwards rather than lost lift and fell - something I�ve never seen in 40 years nor heard of. The 3G sound more like the pull out at the bottom of the drop and sounds a little over aggressive, but I wasn�t there and may be wholly warranted. Never forget though that we are all human and this event would have been unexpected to the pilots - it is possible they may not have handled as smoothly as they would have liked to.

I am just glad I wasn�t flying it - sounds like the pilots were given a tough situation and handled it safely, all any of us could hope for in the same circumstances.

corporate-wage-slave

Welcome to Flyertalk and welcome to the BA Forum.

Thanks very much for letting us know about this, and we're grateful for this insider view.

corporate-wage-slave

Welcome also to you for joining Flyertalk and letting us know about this. And in addition to your experience of why the belt really matters, you have now shared it with many people on here, so that's your good deed for the day out of the way. Hopefully your future use of the BA Forum is for the more pleasureable experiences of making the most of travel.

corporate-wage-slave

And just to thank you for your report too, I think the 3 first hand accounts gives a good perspective of the event.

JerseyPilot

There is no way whatsoever that the aircraft lost 1000’ of altitude in under one second. The forces involved with that would be way outside the design limit load of the airframe and it’s far beyond even free fall speed so not physically possible to start with.

Duck1981

The 'like' button is probably named wrong for this one but thanks for sharing and glad you are ok.

Singapore_Air

I hope everyone recovers and the pax get to their destinations as soon as possible.

Whilst the altitude data shows the aircraft 'only' fell 1,000ft, the speed data shows a dramatic deceleration.

Waterhorse

That is indeed a dramatic speed loss, and would certainly have needed a descent to regain. I suspect etc this is where the 1000ft comes in and probably quite a steep descent ensure a stall recovery was avoided too given that speed loss. A really unpleasant and scary situation for all.

Worthy of note though that it is a ground speed loss not an airspeed loss, so again it�s a little hard to judge

crazy8534

Wow - isn’t that like coffin-corner level speed loss?
Do you think it would be an instrument temporary error/mis-reading?
Or can that really happen in turbulence? (I guess so)
Brilliant work by the crew, whatever.

Waterhorse

Coffin corner is a different phenomena, but as I said it�s only showing ground speed not airspeed. The aircraft only knows airspeed, the speed of air over the wings so ground speed can be deceptive if the tailwind is suddenly a headwind or vice versa it can have a profound impact on GS but much less impact on IAS. Either way it�s an impressive speed loss and they would almost certainly have had to trade potential for kinetic energy and descended

crazy8534

Thanks Waterhorse, appreciate the explanation as always.