Driftdown and Depressurisation

Question 1

Published Driftdown Procedures

Answer 1

For all published driftdown procedures, if the aircraft weight is sufficiently low and aircraft can maintain a sufficient altitude above MOA after an engine failure, then no critical point or escape route are required.

Question 2

Minimum Flight Levels

Answer 2

Due to high terrain the B777 is restricted to higher flight levels on some sectors. Should levels below specified minimum be offered all efforts should be made to negotiate higher levels to avoid a turn back. I.e. delaying, en-route holding or negotiating with other aircraft are all viable options. A RE-ROUTE IS REQUIRED if minimum level or above is not obtained.

Question 3

Fuel Jettison

Answer 3

Although analysis has shown that terrain will be cleared without jettison, if situation permits, it is recommended that fuel jettison be selected as soon as workload permits. Further jettison may be required to reduce below MLW.

Fuel Jettison Rate -
Centre Tank - 2500 kgs/min
Main Tank - 1400 kgs/min

(It take approx 12 mins to descend from 35000ft to 25000ft.)

Question 4

Escape Route

Answer 4

If applicable this MUST be programmed into Route 2.

Procedures will ensure aircraft clears all terrain by at least 2000ft. Aircraft may descend below published flight plan MSA following an IFSD.