BO105 fatal accident back in 2006(?)

[Nubian]

I wonder about if it's not time to bring out the old Aerodynamics notes from PPL ground-school.

Why did we learn to keep collective pitch constant during our first hours?
Cause: The amount of power needed for hover, will allow acceleration and climb away once passed 12-15 kts (ETL) as the whole disc area is now more efficient, generating more lift over drag, than in a hover also making the disc more responsive/controllable.

Why do I drag this into the discussion?!

Well, in his manoeuvre he would turn from up-wind to down wind while decelerating, climbing, and bank hard. About 98 deg. if I remember correctly, so A BIT steeper than your average steep-turn

All of you know that operating down-wind is less favourable than up-wind, and the importance of maintaining IAS. However, if you fly with reference to the ground (in this case for practise for a film-shoot) you might unintentionally loose too much of your IAS, and even loose ETL. Now your disc is generating less lift for drag and it is far less responsive for your recovery actions.

IF in this case, he in fact lost ETL at the top of the manoeuvre, WITH the extreme bank-angle he had (his disc is NOT producing lift vertical to the ground at this point, but acted upon by earth's gravity generating a fairly high ROD), the only thing that could let him recover was to regain ETL by loosing ALT, which in this case he did not have much of...about 70 ft.

Back to the question about the down-wind/up-wind, if that has any effect. If he had done the same manoeuvre opposite direction, I am fairly sure the outcome would be much different as I am sure he wouldn’t have lost ETL and by that maintained control throughout the manoeuvre.

My 2 cents...


There are old pilots and there are bold pilots, but there are NO old bold pilots....

RIP