Sikorsky S-92: From Design to Operations

[Thridle Op Des]

Playing devils advocate slightly, I would just like to remind the readers of the BHL CFIT in China which would certainly have benefited from some form of EGPWS. There is also an apocryphyl though plausible story of a S61 flying out of SUM at 1500' IMC and passed directly over Foula (1300' if I can recollect) they allegedly thought the RadAlt had spiked (must have been a stiff tailwind). This is what happens where we get enviromental capture and fail to properly anticipate the threats - though one could sensibly argue the same for any accident/incident to a greater or lesser degree.

I have just arrived in from a flight to Zurich, while it is not surrounded by the high Alps, it is very nice to have that big terrain awareness picture around you all the time with a strong visual impression of the most threatning bits of granite.

I rather think the issue is money as always - I do have to agree with a comment NL made some months ago when we got into a FW vs RW argument (discussion) that RW will always be the poorer cousin. Many of the systems used by FW would work in RW if the design parameters could take account of the considerable energy and envelope differences each mode of transport has. Sadly the proper R&D will not be undertaken because of the costs; or the liability issues of an accident force the expenditure. It is a fact that the public exposure of a B767 hitting mountains in Cali has a stronger financial motivation than an S76 running into the Gulf on a night NPA.

When you look at the accidents that 212man cites, it would be interesting to see what the result would have been if there was a 'Don't Sink' call every 5 seconds (never mind the accent). How would you design a reliable 'Don't Sink' warning that wouldn't be subject to abuse like the RadAlt bug being set below zero when AVAD is fitted? How does the helicopter know you are sinking because you are actually landing? In the FW world, these issues are relatively simple, we are on an approach on an IFR guidance of some kind and the EGPWS knows the Terrain Clearance Floor for the runway you are landing at. The configuration of the gear and flaps also lends weight to the aircraft intentions. These kinds of cues are not available to a terrain avoidance system in the RW enviroment.

TOD