Unreliable Speed — BUSS

Departure Delhi VIDP RWY 28, cleared to climb 6 000 ft, in cloud with the temperature near zero. PASSING 2 500 FT all three pitot heads ice up together: ANTI ICE ALL PITOT comes up amber, and the FCOM's own warning on that page is the whole exercise — “ADR 1, ADR 2, and ADR 3 speeds will be in agreement, but incorrect.” There is no ECAM alert for the speed itself, no discrepancy, no ADR fault: all three tapes agree with each other and all three are lying. The only thing that gives it away is the cross-check against pitch, thrust and the GPS.

Fly the memory items — AP/FD/A-THR off, 10° and CLB thrust — and level off at the cleared 6 000. Then work the QRH: probe heat on, cross-check every speed indication, find that the affected ADRs CANNOT be identified, and below FL 250 switch ALL THREE ADR pushbuttons off. The PFD speed scale becomes the BUSS and the altitude becomes GPS. From there it is hand-flown in ALTN law: fly the green, no speed brakes, configure with level wings, FLAP 3 for landing, gear down by gravity, back into Delhi on the ILS RWY 28.