Unusual (I think) landing approach

[CrutyRammers]

One for the airliner sorts on here.
We flew into Doncaster yesterday afternoon, 737-800, there were a few decent sized cumulus about, though nothing really bonkers...tops at 15-20,000 feet I'd estimate.
At around 20,000', he deployed the speed brakes (I think - I'm going to get told off for my incorrect terminology here ) - all the inboard spoilers on the top edge of both wings, so we slowed down quite aggressively. A little lower, but still unusually high, and unusually early (going by my normal passengering experience), he put the gear down, causing another considerable deceleration. Still maybe 10 mins from landing, around 10,000'. We took a slightly serpentine course, then did a single circuit, then finally came out of that into a straight final approach, at which point full (or lots, at least) flaps were deployed.

All seemed a little unusual, particularly the use of the speed brakes and the very early gear down. I'm guessing that he was finding a route through some weather (there were definitely rain storms around as we could see them), circled to lose height in some clear air rather than ploughing a straight approach through some lumpy stuff. Just interested in any light anyone can shed

[RobbyJ]

Sounds unlikely that it was anywhere near 20,000ft but you were the one on the plane. Give me the flight number, time and origin and I'll have a look at the data from the flight.

[GliderRider]

It sounds as though you were flying through some very strong thermals, so the pilot was using a combination of extra drag and lift-dumping to maintain his descent and speed profile.

[Chucklehead]

He was too high and side slipping it in

[Simpo Two]

Strong tailwind?

[AndrewGP]

Sounds to me like the crew were high on the descent profile (for whatever reason, could be weather, could be ATC constraints) and needed the drag from the speed brakes and the gear to control the energy.

I’ve never flown the 737 but from my time on the 777 (which is a slippery airframe and can be tricky to slow down) you’d quite often need a bit of brake to control the descent speed if there was any tail wind or if you got high on the descent profile and if all else failed, the teaching was to get the gear down early. Difficult to say if the above is what happened but that’d be my guess.

As an aside, I read Doncaster Airport is closing soon which is a real shame. Fond memories of the place, as I did some of my flying training there when it was RAF Finningley.

[CrutyRammers]

RobbyJ said:

Sounds unlikely that it was anywhere near 20,000ft but you were the one on the plane. Give me the flight number, time and origin and I'll have a look at the data from the flight.

Going from memory and estimating using the cloud tops, so could be way out.
Zakynthos to Doncaster, depart 15:50 Thurs 29th oct, TUI flight 4301 I think...can't check the details today but I think that's right.

[CrutyRammers]

GliderRider said:

It sounds as though you were flying through some very strong thermals, so the pilot was using a combination of extra drag and lift-dumping to maintain his descent and speed profile.

It was well above base, and the descent was fairly smooth in clear air. Late in the day so it would be convective energy rather than thermals, which is what I think he was avoiding.

[MarkwG]

Was this the flight? https://www.flightradar24.com/data/flights/by3401#...

[CrutyRammers]

MarkwG said:

Was this the flight? https://www.flightradar24.com/data/flights/by3401#...

Yep, thanks. 3401 not 4301. Always interesting to see how bad memory is; I could have sworn that we did a full 360 prior to landing, but actually just 180.
So, speedbrake to bring it down from 400+kts to 340 ish at around 18000', gear down around 12000' perhaps.

[MarkwG]

CrutyRammers said:

MarkwG said:

Was this the flight? https://www.flightradar24.com/data/flights/by3401#...

Yep, thanks. 3401 not 4301. Always interesting to see how bad memory is; I could have sworn that we did a full 360 prior to landing, but actually just 180.
So, speedbrake to bring it down from 400+kts to 340 ish at around 18000', gear down around 12000' perhaps.

I doubt it was the speed brakes, my understanding is they're limited to speeds below 300kts on the NG 737, but perhaps a pilot who flies them may interject. Similarly, I doubt the gear would be down that early, I'd expect somewhere between 15 & 8 miles out, as the speed decays through 180kts. Without overlaying the airspace it's difficult to get the whole picture, but it looked like a fairly normal approach to me,

[Crumpet]

I don’t have the paid for version of Flight Radar so can’t check vertical speed but nothing about it looks too unusual (if you can view it have a look to see if the rate ever gets more than 2500-3000fpm or so). Looks to have been at about 15,000’ with about 45 miles to run and then nicely on profile from there.

Of course that doesn’t mean the speed wasn’t running away a bit, for various reasons, so the spoilers and early gear would just help control it. I believe the 737 has a pretty high gear extension speed so could well have had them dropped early and high.

[CrutyRammers]

Crumpet said:

I don’t have the paid for version of Flight Radar so can’t check vertical speed but nothing about it looks too unusual (if you can view it have a look to see if the rate ever gets more than 2500-3000fpm or so). Looks to have been at about 15,000’ with about 45 miles to run and then nicely on profile from there.

Of course that doesn’t mean the speed wasn’t running away a bit, for various reasons, so the spoilers and early gear would just help control it. I believe the 737 has a pretty high gear extension speed so could well have had them dropped early and high.

Yeah, fair enough. It just seemed different enough to usual to make me wonder what was going on The track looks a lot more "normal" than it felt.

[peter tdci]

Crumpet said:

I don’t have the paid for version of Flight Radar so can’t check vertical speed but nothing about it looks too unusual (if you can view it have a look to see if the rate ever gets more than 2500-3000fpm or so). Looks to have been at about 15,000’ with about 45 miles to run and then nicely on profile from there.

Of course that doesn’t mean the speed wasn’t running away a bit, for various reasons, so the spoilers and early gear would just help control it. I believe the 737 has a pretty high gear extension speed so could well have had them dropped early and high.

The flight path shows a descent from cruise down to 18,000ft, then down to 12,000ft and a continuous descent before landing. The FL data showed rates of over 3,500 fpm during each of these.

Here's a screenshot as it was passing through 10,000ft, but is doing almost 300kn (isn't the gear extension limit for 737s about 270kn?)

[Crumpet]

peter tdci said:

The flight path shows a descent from cruise down to 18,000ft, then down to 12,000ft and a continuous descent before landing. The FL data showed rates of over 3,500 fpm during each of these.

Here's a screenshot as it was passing through 10,000ft, but is doing almost 300kn (isn't the gear extension limit for 737s about 270kn?)

That’s a True Airspeed of roughly 300 so an Indicated Airspeed of about 250 - the standard speed limit below 10,000 feet. Gear and flap limitations are based on indicated so all good in that regard.

In any case, those vertical rates of 3500fpm are a bit more than you’d normally expect and as a passenger with the noise of the spoilers it would seem…..unusual. Especially with the 4000+fpm on that flight radar screenshot!

It looks like it was indeed perhaps a bit sportier than normal but nothing too exceptional. Some days you just get screwed over - either by ATC or slower traffic - and end up too high. Some days you screw your descent planning up yourself. Some days you might want to stay high to avoid some build ups and then drop down into the gap beyond them. On the aircraft I fly it can be a pain in the arse if you’ve got the anti-ice systems on as the engines idle with increased thrust to provide the hot bleed air for the bits you don’t want ice on. The extra thrust means the aircraft just wants to fly and the descent rate is significantly reduced. So you then need spoilers and to the passengers it sounds and feels rough.

Edited by Crumpet on Monday 3rd October 21:33

[anonymous-user]

These height profiles come from some of the airspace being uncontrolled to the east (class g) so you have higher heights than normal to the east with height restrictions above profile to remain within controlled airspace. If you’re high then you need speedbrake and maybe even gear early to get the height off before intercepting the localiser and glideslope for the ils.

The “180” is pretty normal in Doncaster coming in from that direction.

Typically you can expect restrictions of at or above fl160 (16000ft) at position Vegus and 12000ft until another position which I can’t remember tbh.

I’ve superimposed a chart showing these waypoints on your fr24 map of your route so you can see where position vegus was.

Edited by anonymous-user on Monday 3rd October 22:00

[CrutyRammers]

Ah-ha, so I wasn't going entirely mad then. And my height estimate wasn't miles out either

Surprised the descent rate was so high; I felt deceleration rather than descent (I understand how we feel acceleration rather than speed), but that's over -20m/s; if I was doing that on my paraglider, I'd certainly know about it!

Thanks to all those who've replied, always interesting to see what actually happened compared to memory.