Dash8-300,-400 steep approaches

[OverRun]

I’m sitting as part of an ICAO country assistance team, deep in the southern hemisphere. One of the local operators is using Dash 8-300/400 aircraft at an airport with a steep approach. The approach is 7 degrees, due to terrain.

Has the Dash 8-300 or -400 ever been certificated for steep approaches?

I know a little about this issue from LCY, but I am an airport engineer not a pilot, hence my specific ignorance on the Dash 8. I know the similar-sized ATR72 has been certificated for steep approaches, which I guess is because of the need to operate to those Alps airports with steep runways and approaches. But the Dash 8? Appreciate any inputs on this. Cheers.

[John Farley]

I was once asked to certificate a type for steep approaches. This was only needed because the owner wanted to use it at LCY where the regs required such certification.

I wonder if all airfields that need a steep approach actually require the type to be certificated at the appropriate angle or whether some leave it to the common sense of the operator not to fly into them unless the type's handling is OK?

Not answering your question I know but could be relevant?

JF

[KingDingaling]

Hi,

I know that the Q400 has been certified for steep approaches and there is an operator taking the 300 into LCY so I assume that has too. Not sure what angle of approach the certification extends to though (if any). One can only assume its been certified for the 7 degrees if they are flying it?

KD

[renard]

Air Southwest fly Dash 8's into LCY, not sure which variant.

Augsburg on behalf of Lufthansa fly Dash 8 100's into LCY.

Fly Baboo fly Dash 8 Q400 into LCY.

[excrab]

Overrun,

The 200, 300 and 400 have been certificated for steep approaches. Don't remember the exact details but there was a mod to the EGPWS which had to be armed prior to the approach, and of course also an addition to the aircraft flight manual.

Probably the best people to contact would be Bombardier Regional Aircraft in Toronto (google as I don't have the address to hand), who will be able to give you all the technical detail.

200, 300 and 400 series have all been operated into LCY by various operators.

[Piece of Cake]

Presently the Q400 is certified to conduct steep approaches up to 5.5 degrees.

Other limits apply, such as<5 knots tailwind, runway slope 0.5% or less, minimum Decision Height at least 300ft etc.

Approaches have to be flown with Flaps 35, autopilot and FD off. However not all Q400s have been modified for steep approach.

(As part of the certifcation process the aircraft will have had to demonstrate it is capable of following a glide path of up to 2 degrees steeper than the published appraoch angle).

PM me if you need any more info.

Best Wishes,

PoC

[OverRun]

Thanks everyone - that is exactly what I need.

Cheers
Overrun

[safetypee]

OverRun if, as it appears, the operator would be seeking more than 5.5 degrees (Q400), some aircraft have negotiated less certification margin (< 2 deg) in exchange for a no-tailwind limit. However, if the ultimate steep approach capability of the Q400 is 5.5 deg, I would not expect the loss of 5 kts tailwind to provide more than 0.5 deg descent improvement.
Another ploy is to check if a reduction in the airframe systems requirements might give more performance e.g. the need to spool up engines to provide anti-ice air bleed. I doubt if this helps with a Q400.
A more desperate measure might be to differentiate between a ‘runway’ approach – straight in landing, normally associated with a precision approach aid (for which the steep approach regulations were written), and an ‘airfield approach’, where there may be no requirement for an aircraft steep approach certification, or less requirement for a maneuver margin i.e use 5.5 deg + 2 deg margin for a 7 - 7.5 deg approach. There were examples of this at Lugano and at Aspen, before the MLS arrived. IIRC subsequently both airports managed to ‘negotiate’ a procedure for straight-in landing, but I would not recommend this for low minima in poor weather. Also, this could present additional problems with EGPWS beyond capability of the existing modification.

[OverRun]

Many thanks safetypee; indeed the debate is going on about the type of approach. The 'airfield approach' might well be a better way to go here, and I shall facilitate the thought with the flying ops people. Along with the tailwind options, EGPWS, etc.

One minor side-track is a new thought this week that there must be a PAPI installed at a 7 degree glideslope so as to facilitate the approach. The PAPI design can be done for that glideslope from fundamental principles, but actually mounting the baseplate on the ground so it can be adjusted to give a 7 degree angle is less easy. The original thought was that the runway is not a precision approach runway, and a PAPI is just not needed. Still not got the answer on that on, and if anyone has ideas, I'd also appreciate those.

Make one minor change from the normal operation, and many other changes follow faithfully along, close behind, each juggling a piece of swiss cheese in the air, trying to line up the holes. . . .

[safetypee]

OverRun re “… PAPI is just not needed.”
The original ‘jet’ certification at LCY required ‘precision’ approach guidance, being either ILS GS or PAPI; thus if the ILS is u/s, PAPI is mandatory.

IIRC LCY had PAPI for the DHC-7 operations (7.5 deg), and many pilots viewed this aid as essential. I would agree, and would not plan any steep approach greater that 4.5 deg without some form of vertical reference, e.g. PAPI or altitude/DME.

Insufficient PAPI angle – tilt the earth; then stick a leveling bubble on the side of the unit for future reference.

An accurate approach should help stopping performance – having arrived at the threshold with improved accuracy it is still necessary to stop; more holes in the Swiss Cheese.

[OverRun]

Thanks again safetypee. A bubble it shall be (and what an elegantly simple solution). Ready for flight checking.

And that also puts the PAPI discussion firmly to bed. Much appreciated.

Overrun