Mr Spaceman From Canada, joined Mar 2001, 2787 posts, RR: 8 Posted (11 years 7 months 1 week 4 days 22 hours ago) and read 2407 times:
Yesterday I was relaxing in a park near my home while listening to my air band receiver and watching airliners as they were turning from left base to final for Toronto Intl's rwy 24R.
I was there for hours, and as 6:00 pm & the busy hub time approached, ATC had the airliners flying farther outbound on their downwind legs before being turned onto base ..... as usual. They were flying their base leg dirrectly above me at 15 nm DME from 24R's threshold. Most of these airliners were maintaining 170 knots through their base leg & final approach untill reaching the outer marker.
Then, at 6:15pm I spotted a Northwest Airlines A319 (flt 1830 from Detroit) on base leg with it's gear already extended! This caught my attention because I have never seen an airliner with it's gear down while this far out on base leg in the past 7 years that I've lived here. Airliners usually extend their gear while on final & around 8 nm DME from the rwy.
My question is ..... What's the most likely reason why the pilots of this A319 had their gear down so early? Do you think they might have been having problems with their hydraulics & decided to put the gear down while they could?
Mr Spaceman From Canada, joined Mar 2001, 2787 posts, RR: 8
Reply 2, posted (11 years 7 months 1 week 4 days 21 hours ago) and read 2372 times:
I thought about that possibility too. I guess that could be the answer, however, the traffic was pretty heavy in the pattern, so I'm sure this A319 would have needed to be slowed right down to 190-170 knots way back on his downwind leg or sooner to keep from getting to close to the next aircraft ahead.
After years of watching thousands of airliners fly over my home on their left base leg for YYZ's rwy's 24L, 24R, & 23, I've never seen one with it's gear already down.
FSPilot747 From United States of America, joined Oct 1999, 3599 posts, RR: 12
Reply 3, posted (11 years 7 months 1 week 4 days 20 hours ago) and read 2346 times:
I have to agree with Ikarus.
Flaps are the first form of slowing down, gear are the second, and speed brakes come next. It's very possible that they needed to slow down a bit before turning onto base. It's not so far fetched. On the A319/20, you can't extend the speed brakes when flaps are fully extended.
Rick767 From United Kingdom, joined Jan 2000, 2662 posts, RR: 51
Reply 4, posted (11 years 7 months 1 week 4 days 19 hours ago) and read 2326 times:
The A319 is a slippery little b****rd on descent (I know this from jumpseat experience). Full speedbrakes and idle thrust are sometimes simply not enough to get this bird to go down and slow down.
Like the 757, deceleration on descent generally requires a level flight segment. The crew must extend the gear to produce some drag and slow down. We do the same on the 757, often a long way out if ATC have kept us high / fast.
"Flaps are the first form of slowing down, gear are the second, and speed brakes come next"
Not that order at all. Speaking from 757/767 experience, Speedbrakes are the first, if full speedbrake does not create enough drag then gear can be extended early. Flaps should never be used to decelerate the aircraft, they should only be selected to the appropriate setting when passing the maneouvre speed for that setting and decelerating.
This is extremely important as selecting flaps at speeds above this in an attempt to decelerate places a huge stress on the mechanism and will reduce the life of the flaps significantly (according to our tech guys).
Fatigue life calculations made by Boeing assume the flaps are being operated with strict adherence to the flap schedule (for both climb and descent). Excessive loads could cause failure before their predicted life is completed.
Sorry to sound "harsh" on this matter but it is really important and stressed to us in training to no end. If I had a dollar for every time travelling as a passenger when I have heard other passengers tell people the flaps are to slow the aircraft down . They must never be used for that.
I used to love the smell of Jet-A in the morning...
Positive rate From Australia, joined Sep 2001, 2143 posts, RR: 1
Reply 5, posted (11 years 7 months 1 week 4 days 18 hours ago) and read 2306 times:
I've seen some airliners extending their landing gear as far as 13-14 NM's from touchdown. It's for seperation purposes. If you've noticed the planes are much louder when they come in slower, probably because they need more power to maintain the glidepath with gear and full flap out. Even the 737 is one noisy bugger when back at minimum approach speed.
Vikkyvik From United States of America, joined Jul 2003, 10759 posts, RR: 26
Reply 6, posted (11 years 7 months 1 week 3 days 22 hours ago) and read 2152 times:
On a tangent to Rick767's post...I was flying to LAX a couple days ago in a A320 and had a seat with a view of the wing. The spoilers were fully extended for a large portion of our final approach, right up to around the 110 freeway, which I think is around 6 miles from the airport.
Mr Spaceman From Canada, joined Mar 2001, 2787 posts, RR: 8
Reply 7, posted (11 years 7 months 1 week 3 days 22 hours ago) and read 2153 times:
Thanks for your replies.
OK, so the most likely reason why this A319 had it's gear out while on base was to help slow the slippery little bast*rd down. I guess I suspected a mechanical problem (such as low hydraulic pressure, etc), because I had never seen an airliner with it's gear down on base before. Also, it was already extended as the A319 was turning from downwind to base, which FSPilot747 explained is very possible.
Today I spotted off in the distance, a 747 on a straight in approach with it's gear already extended while floating down the glidepath for rwy 23 at about 18 dme from touchdown. That's not a usual sight, but, now I know the main reason for it.
> Rick767, I remember our friend AAR90 explaining that the AA 737-8 that he flies doesn't slow down to easily & that the engines are usually at idle for most of the final approach profile.
Hear at YYZ, it's normal for the controllers to have the airliners maintain level flight at several different altitudes untill down to 4000 or 3000 feet before turning onto base. Then they're instructed to maintain that altitude untill they intercept the ILS's glideslope. So they normally get many level flight segments after checking in with arrival.
Regarding flap settings and VFE speeds for the A319, they're clear in this photo .....