Flight on Dash 8 400 series

[frequentflyer2]

I want to ask a question about a recent short flight on a Dash 8 400 series aircraft but before I do I'll just make it clear I am not a pilot; know nothing about flying a plane and do not pretend in any way to be more expert than the two flight crew in the cockpit of the aircraft. It is a genuine query which I would be grateful if someone could answer.

On Friday evening my wife and I flew from Glasgow to Belfast City on a Flybe Dash 8 400 Series.
The flight crew began the take off acceleration before turning on to the runway which I know is quite a normal procedure.
However, we have flown on the Dash 8 400 many times and the take-off run went on.....and on.....and on.
Normally this is an aircraft which lifts off very quickly but on this occasion it remained on the ground until well past the terminal building and the V2 sign on the runway.
We approached BHD over Belfast Lough and again I'm not claiming to know anything about piloting this aircraft.
However, at this stage the aircraft was definitely moving much faster than normal and crossed the threshold much higher than normal, touching down further along the runway than normal. The only thing I can think of is we were landing with a tailwind just within the operating perameters of the aircraft.
But why the long take-off run? Can anyone explain?

[Chesty Morgan]

As Glasgow has a fairly long runway I would hazard a guess that they would have used the lowest flap setting and the lowest power setting that the performance allows.

Effectively, within the take off performance constraints, you would have observed the lowest level of acceleration to the highest take off speed available on that particular runway.

This generally benefits the airline as it puts less wear and tear on the engines and flaps although with the higher take off speed you will get more wear on the wheels etc..

[FL370 Officeboy]

Sounds like a heavy aircraft and small headwind component to me. I've done a few 'long' takeoff rolls in the Dash and they are rare I agree but the do happen. A heavy aircraft would also have had a higher approach and landing speed.

Glasgow's runway does allow full de-rate takeoff (81%) with minimum flap setting (flap 5). They could also have been tanking fuel etc to take the aircraft toward the upper end of the weight/performance envelope. As you correctly noted too, it could have been a landing with a tailwind component, to allow a straight in approach onto runway 22 from the north.

All I can say is don't worry about it...it's in the pilots interests to operate safely and get home in one piece too :)

[speedrestriction]

Were there many passengers on board? A heavier aircraft needs to fly faster for both takeoff and landing using more runway in both cases. If an aircraft is operated outside of its operating envelope the company will be alerted to this fact by FDM (Flight Data Monitoring) which is mandatory on aircraft of that size.

Without in any way wishing to sound dismissive: perceptions of speed and height are very subjective and will vary significantly even amongst what one could regard as informed observers.

[G SXTY]

Indeed.

Rotation (take off) speed on the Q400 could be anywhere from around 105 knots to 130 odd, depending on power, flap setting, aircraft weight and runway length. At low weights and 'full' power (actually only 90% to be precise) it goes like a rocket, and is off the ground very quickly indeed.

However, in much the same way as you wouldn't thrash your car's engine every time you accelerate down a motorway slip road, we use reduced power whenever possible (as low as 81%). On a long runway this usually involves a lower flap setting as well, and - especially at high weights - acceleration is rather more leisurely. The take off roll at Glasgow would certainly be longer than Belfast City.

Regarding your perception of the landing, I find it impossible to judge groundspeed from the cabin, and I fly them for a living. The aircraft is certified to land with a tailwind and the touchdown zone is reasonably large, so I very much doubt you experienced anything out of the ordinary. BHD isn't the longest of runways, so if there was anything unsafe about the approach or landing, the crew would have gone around - it involves much less paperwork than going off the end of the runway.

[Otto Throttle]

For Friday evening, the assumptions above would most likely be correct - fuel is currently relatively expensive in Belfast City, so crews bring in as much cheap fuel from elsewhere as they can, and the airport had been landing on runway 04 most of the day. Approaching down Belfast Lough would mean landing on runway 22, which is the opposite end, and if the weather was the same as it had been earlier in the day, probably involved a tailwind of around 7-8 knots, well within the allowed limits for the Dash.

[Floppy Link]

...the V2 sign on the runway...

The what?
:confused:

[Contacttower]

...the V2 sign on the runway...

Possibly a holding point sign, although while I believe Glasgow has a Z2 and a Y2 I'm not sure it has a V2. Perhaps frequentflyer2 mistook V for another letter.

[frequentflyer2]

Actually, it was Mrs. FF who was sitting at the window and believed she saw a sign saying V2.
Remember, I'm not a pilot so I thought perhaps it meant aircraft should be at V2 at that point or else abort the take-off.
All the flight crew reading this are probably rolling in the aisles now so if such a sign does not exist all I can say is it was a genuine mistake.

[Contacttower]

All the flight crew reading this are probably rolling in the aisles now so if such a sign does not exist all I can say is it was a genuine mistake.

No such sign exists (although I can see it might a reasonable assumption to make by a non-pilot)...there is such a huge variation in the performance of different aircraft that it wouldn't really make sense to have such a thing.

Most of the signs one sees down the side of a runway mark exit points and taxiways, they will have a designation such as 'Y2' or 'A1' or whatever so that ATC can tell aircraft which one to use when moving around on the ground.

[PaperTiger]

The V2 "sign" is those red lights at the end of the runway.