Flybe Incident at Amsterdam
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Nil marks for giving it a boot full to straighten it out after decking the sbd gear.
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Does anybody know what Prop RPM Flybe normally use in heavy wind conditions? Do the always use 850 whenever not limited by the supplements, or is 1020 the preferred setting on a day like this?
GearDownThreeGreen,
in such wind conditions, I dare say that there are only very few DH8D pilots that would not select 1020 rpm for an approach.
This makes the aircraft much more responsive to power lever movements and allows for much quicker corrections of gusts. And besides that, it is formally required by our (not FlyBE) OM-B (among others) in turbulent conditions. The main downside besides a bit more cabin noise is that careful handling of the power levers in the flare is required. Even more so than with 850/min, ham-fistedly pulling them back will result in an immediate descent if already low on energy or encountering a performance-decreasing gust and may lead to a rather solid touchdown.
C195,
a typical duration for the DFDR recording is 25 flight hours. The FQAR (for flight data monitoring) records up to 320 flight hours.
in such wind conditions, I dare say that there are only very few DH8D pilots that would not select 1020 rpm for an approach.
This makes the aircraft much more responsive to power lever movements and allows for much quicker corrections of gusts. And besides that, it is formally required by our (not FlyBE) OM-B (among others) in turbulent conditions. The main downside besides a bit more cabin noise is that careful handling of the power levers in the flare is required. Even more so than with 850/min, ham-fistedly pulling them back will result in an immediate descent if already low on energy or encountering a performance-decreasing gust and may lead to a rather solid touchdown.
C195,
a typical duration for the DFDR recording is 25 flight hours. The FQAR (for flight data monitoring) records up to 320 flight hours.
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Ahh. The baby duck walk of the PLs at max RPM landings is quite extreme, yes. Our OM-B does not mandate 1020 RPM, however everybody does it in high/gusty winds anyway. I was just curious about Flybe's procedure around this, and I guess it's safe to assume they have revved up the props then...
Yes, you are. For an 850rpm landing, a button is pressed that locks the RPM at that value, but the condition levers are set to max. When a certain power lever angle is exceeded thereafter, the "lock" is opened and the propellers spin up to 1020rpm. This is mostly intended for the go around case, but in very gusty conditions, it might happen inadvertently as well (as Tojo-san referred to). Also when one pushes the power levers beyond the rating detent, the propellers will be automatically set to 1020 regardless of C/L settings in order to avoid an overtorque as long as possible.
The Va increment du jour on the DH8 depends on more factors than just wind. I´ll try to keep the answer as short as possible. And of course, I refer to the book as used in my company, the OM-B of FlyBE may vary as Bombardier allows for a bit more freedom in operating its aircraft than many other manufacturers.
For a beautiful, calm/cavok day on a non-limiting runway, we are generally requested to fly Vref+10 for flaps 15 and Va+5 for flaps 35. This applies to about 90% of approaches, but certainly not to this one.
But then along come the exceptions. I will restrict myself to those that may be applicable to the situation the Flybe colleagues faced, there are some others as well.
- For wind, the recommended correction is 1/3 the steady wind OR gusts (whichever is higher), but not more than +20kts. Below 9 kts wind speed this is covered by the standard +10kts (flaps 15), but above that, the actually flown speed will be increased.
- In icing conditions (on the DH8 inflight, they are defined as OAT below +6°C AND visible moisture), the icing speeds Va-Ice apply. Those are generally the basic Va speeds plus a fixed increment of 15 (Flap 35) to 20kts (Flap 15). This speed is flown as it is and not increased for other factors any more: the risk of a nose wheel landing would become too high otherwise especially with flaps 35°. The reason for this increment is the de-icing equipment of the aircraft: the boots will not clear the leading edge completely the way a "hot wing" would, and the extra speed caters for some residual ice.
The weather (...FEW022... 8/4... -RA) at the incident time as reported on ASN would probably show icing conditions as per above definition at the stabilisation gate (1000ft AAL). So if they faced icing conditions, they likely chose Va 15 ICE with the corresponding increment of 20kts. If not, the increment derived by above formula will probably not have been far below it.
For a beautiful, calm/cavok day on a non-limiting runway, we are generally requested to fly Vref+10 for flaps 15 and Va+5 for flaps 35. This applies to about 90% of approaches, but certainly not to this one.
But then along come the exceptions. I will restrict myself to those that may be applicable to the situation the Flybe colleagues faced, there are some others as well.
- For wind, the recommended correction is 1/3 the steady wind OR gusts (whichever is higher), but not more than +20kts. Below 9 kts wind speed this is covered by the standard +10kts (flaps 15), but above that, the actually flown speed will be increased.
- In icing conditions (on the DH8 inflight, they are defined as OAT below +6°C AND visible moisture), the icing speeds Va-Ice apply. Those are generally the basic Va speeds plus a fixed increment of 15 (Flap 35) to 20kts (Flap 15). This speed is flown as it is and not increased for other factors any more: the risk of a nose wheel landing would become too high otherwise especially with flaps 35°. The reason for this increment is the de-icing equipment of the aircraft: the boots will not clear the leading edge completely the way a "hot wing" would, and the extra speed caters for some residual ice.
The weather (...FEW022... 8/4... -RA) at the incident time as reported on ASN would probably show icing conditions as per above definition at the stabilisation gate (1000ft AAL). So if they faced icing conditions, they likely chose Va 15 ICE with the corresponding increment of 20kts. If not, the increment derived by above formula will probably not have been far below it.
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They almost definitely would not have been flying icing Vref speeds with that METAR.
Vref additive would have been half the gust factor up to a max of vref+15. It was blowing 31G46 according to avherald so Vref plus 7.5kts.
Vref additive would have been half the gust factor up to a max of vref+15. It was blowing 31G46 according to avherald so Vref plus 7.5kts.
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Melbourne on a gusty northerly day, it's not unheard of to have 300/30 gusting 50 kts for landing on RWY 34, so pretty familiar with landing in similar conditions.
In our operations, our additive is 1/3 of the wind, or all of the gust, up to an additive of 15 knots. So I'd have had an addition of 15kts on top of Vref.
Also would have landed 1020 rpm and FL 15. Also guessing that I'd have a bit of power on, on touchdown.
Yeah right....
You're going to fly vref + 7.5 in those conditions? IMHO, it is exactly this mentality that will result in heavy landings.
In our operations, our additive is 1/3 of the wind, or all of the gust, up to an additive of 15 knots. So I'd have had an addition of 15kts on top of Vref.
Also would have landed 1020 rpm and FL 15. Also guessing that I'd have a bit of power on, on touchdown.
Vref additive would have been half the gust factor up to a max of vref+15. It was blowing 31G46 according to avherald so Vref plus 7.5kts.
You're going to fly vref + 7.5 in those conditions? IMHO, it is exactly this mentality that will result in heavy landings.
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Is the use of mobile phones in the cabin now permitted? I see quite a few videos taken from inside aircraft using mobile phones. Is it OK just to disregards piolots instructions when flying?
Bombardier is not as strict about the operation of the aircraft than other manufacturers and gives its customers many liberties in designing their own OM-B. So when I write about SOPs in my company, they need not apply to other companies at all. The general spirit is likely the same, but in details, there may well be substantial differences.
I will refrain from discussing such SOPs from now and leave that to any interested FlyBE colleague.
The DH8D is generally considered not an easy aircraft to land. Reasons for this are e. g. the large speed spectrum between plain Va and Va+20 on short final, the differences in approach pitch both due to these speed differences and different flap settings (with Va and flap 15°, a pitch of 2-3° is not untypical while flap 35° and Va-ICE may show a pitch of -3 to -4°, both in a stabilized final approach). Also the flap setting makes a world of difference: while with flap 15°, drag is rather low and an early (ish) power reduction is appropriate, flap 35° will not only result in some background buffet but also lend the aircraft a drag coefficient of a proper Amish barn. Careful handling of the power levers is required. Also the prop RPM makes some difference; speed control is much more responsive with higher RPM than with lower (compare a car at 1st speed vs. 4th). And to top it up, a pitch at touchdown of -0,5° may result in a nosewheel landing while from +5°, you are in tailstrike territory. Not much wriggle room there.
Bleeding off the speed is therefore not so much a function of the flare height but of power lever handling; the same can be said for the length of the flare, although here the height comes into play as well. Using power to break the descent works on the type as well but is sternly frowned upon by my company at least due to the unpredictable influences on landing performance.
I find that starting a flare in 30-50ft, simultaneously raising the nose and slowly reducing power as needed, thereby assuming the desired pitch for landing and adjusting the sink rate via power, works rather well on this aircraft and results in power-off touchdowns, some soft(ish), some more noticeable.
All this is of course fine and dandy in theory, but then along comes such a weather as the colleagues encountered at AMS. The most thought-out and well flown roundout and flare can quickly go south when a nasty gust shows up at the right time.
I will refrain from discussing such SOPs from now and leave that to any interested FlyBE colleague.
The DH8D is generally considered not an easy aircraft to land. Reasons for this are e. g. the large speed spectrum between plain Va and Va+20 on short final, the differences in approach pitch both due to these speed differences and different flap settings (with Va and flap 15°, a pitch of 2-3° is not untypical while flap 35° and Va-ICE may show a pitch of -3 to -4°, both in a stabilized final approach). Also the flap setting makes a world of difference: while with flap 15°, drag is rather low and an early (ish) power reduction is appropriate, flap 35° will not only result in some background buffet but also lend the aircraft a drag coefficient of a proper Amish barn. Careful handling of the power levers is required. Also the prop RPM makes some difference; speed control is much more responsive with higher RPM than with lower (compare a car at 1st speed vs. 4th). And to top it up, a pitch at touchdown of -0,5° may result in a nosewheel landing while from +5°, you are in tailstrike territory. Not much wriggle room there.
Bleeding off the speed is therefore not so much a function of the flare height but of power lever handling; the same can be said for the length of the flare, although here the height comes into play as well. Using power to break the descent works on the type as well but is sternly frowned upon by my company at least due to the unpredictable influences on landing performance.
I find that starting a flare in 30-50ft, simultaneously raising the nose and slowly reducing power as needed, thereby assuming the desired pitch for landing and adjusting the sink rate via power, works rather well on this aircraft and results in power-off touchdowns, some soft(ish), some more noticeable.
All this is of course fine and dandy in theory, but then along comes such a weather as the colleagues encountered at AMS. The most thought-out and well flown roundout and flare can quickly go south when a nasty gust shows up at the right time.
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Yes, electronic devices are permitted. Has been that way for a few years. As long as they don't do any transmission while flying.
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Only Flap 35 (full flap) landings can tend to be flat due to the low pitch attitude approach angle. This is exacerbated if too high a speed is flown over the threshold, and not enough power is taken off in the flare. I don't think nosewheel first landings are very common, but you do see a fair few flat landings with Flap 35. From reading comments above, it would appear different operators have different philosophies on flap setting on a rough day. Whilst I found Flap 15 to be more comfortable and feel more stable in high winds, Flap 15 had a much smaller margin to tailstrike so Flap 35 was almost always the choice on a rough day.
I don't think I suggested that anyone try to fly a Dash 8 at exactly Vref + 7.5kts but that is the official additive, based on one operators approved SOPs. I have absolutely no idea how flying 7 or 8 knots above Vref "is the sort of mentality that causes heavy landings". You would tend to reduce to Vref over the threshold and (again as per the manual) land at Vref -6 or -7 with power levers at idle. What I have just described is as per the book. In practice I think it's difficult to attain this theoretical landing technique. Especially on a day like that in AMS. It always ended up as a delicate balance between getting the pitch and power correct to touch down in the right place at the right speed, without making anyones teeth fall out or floating down the touchdown zone. I very rarely landed with idle power. It is an awkward machine to get on the ground, but as you say an application of power will very quickly arrest a sink rate on short final.
I don't think I suggested that anyone try to fly a Dash 8 at exactly Vref + 7.5kts but that is the official additive, based on one operators approved SOPs. I have absolutely no idea how flying 7 or 8 knots above Vref "is the sort of mentality that causes heavy landings". You would tend to reduce to Vref over the threshold and (again as per the manual) land at Vref -6 or -7 with power levers at idle. What I have just described is as per the book. In practice I think it's difficult to attain this theoretical landing technique. Especially on a day like that in AMS. It always ended up as a delicate balance between getting the pitch and power correct to touch down in the right place at the right speed, without making anyones teeth fall out or floating down the touchdown zone. I very rarely landed with idle power. It is an awkward machine to get on the ground, but as you say an application of power will very quickly arrest a sink rate on short final.
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Because of the tail strike issue, its recommended by Bombardier to arrest sink below 400 feet with Power lever movement only, as some one mentioned you are not going to fly VREF plus 7 on a day like that the thing is really speed unstable even on a calm day.
you learn quickly on the Q400 if you try to fly VREF plus a bit and power levers close to flight idle your either smashing the tail up or shattering pax teeth.
you learn quickly on the Q400 if you try to fly VREF plus a bit and power levers close to flight idle your either smashing the tail up or shattering pax teeth.
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This flight should have originated from Dundee but the route was switched to Edinburgh in November for reasons that, AFAIK, have not been disclosed. To what extent did the approach and landing characteristics that have been described in this thread contribute to the switch to Edinburgh and to what extent was it the characteristics of Dundee's approach procedures and runway? Or was it a combination of the two? Or some other reason?
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To what extent did the approach and landing characteristics that have been described in this thread contribute to the switch to Edinburgh and to what extent was it the characteristics of Dundee's approach procedures and runway?
Highlands and Islands Airports Ltd, that runs the airport, blamed Flybe: Airport blames Flybe as Dundee-Amsterdam flights axed
Extensive discussion in the Dundee forum here on PPRuNe: www.pprune.org/airlines-airports-routes/204666-dundee-42.html, page 42 onwards. Porrohman, I see you were in that discussion.
Besides Dundee itself there are small airfields around, and I think there's still a university air squadron at the former RAF Leuchars, probably all contributing to the "high levels of light aircraft activity".
Last edited by OldLurker; 1st Mar 2017 at 12:09. Reason: Detail