Heathrow and altitude fix at 6,000ft?

Heathrow and altitude fix at 6,000ft?

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Ari

Original Poster:

19,328 posts

214 months

Wednesday 13th June 2012
quotequote all
Flew out of Heathrow for the first time this week (remarkably. Is usually Gatwick or Standstead). Anyway, we take off, all good, suddenly power winds off and we stop climbing, help..!

We bump along at 6,000ft (airplane has those monitors that show position and height/speed/air temp) with me panicking that something dreadful has happened then after a couple of mins, power back on and up we go.

Looking at the map thing, the power seemed to go back on more or less level with the M25. So is there something that means planes climb to six thousand and hold at that till they clear London? And if not, any ideas why?

LHRFlightman

1,925 posts

169 months

Wednesday 13th June 2012
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At 6000 you'll be flying under one of the four stacks. Give me the date and flight number and I'll confirm tomorrow

Chuck328

1,580 posts

166 months

Wednesday 13th June 2012
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So, flying out of Gatwick or 'Standstead' you have never noticed that you will usually stop climbing shortly after take off at these airports? NO you probably wouldn't notice without a map thing.

Busy London airspace often means an unrestricted climb to altitude is often impossible. Seriously, if that makes you panic, stick to the train...

peter tdci

1,752 posts

149 months

Wednesday 13th June 2012
quotequote all
If the engines are still running, then it's usually ok! There's also a speed limit below a certain height, so if that was being enforced the change in acceleration would be more noticeable if the aircraft levelled off and maintained its speed at that limit.

Ari

Original Poster:

19,328 posts

214 months

Wednesday 13th June 2012
quotequote all
Chuck328 said:
So, flying out of Gatwick or 'Standstead' you have never noticed that you will usually stop climbing shortly after take off at these airports? NO you probably wouldn't notice without a map thing.

Busy London airspace often means an unrestricted climb to altitude is often impossible. Seriously, if that makes you panic, stick to the train...
It's never happened (to me) coming out of Gatwick or Stansted (well done you on pointing out a spelling error!! Did you know you wrote "often" twice in the same sentence?) Map or no map, its a pretty obvious reduction of power. Normally they power back a bit after a minute or two, but the plane is still obviously climbing. It was the power shutting down and the lack of climb that made me look at the screens not the other way around.

And yes, very nervous flyer but sadly the train doesn't get me where I need to be (at least, not the same day!)


Ari

Original Poster:

19,328 posts

214 months

Wednesday 13th June 2012
quotequote all
LHRFlightman said:
At 6000 you'll be flying under one of the four stacks. Give me the date and flight number and I'll confirm tomorrow
Ah, that makes sense, thank you. I wondered whether it was some sort of noise or pollution nonsense but it didn't seem very likely.

I'll get the flight number and let you know.

Ari

Original Poster:

19,328 posts

214 months

Wednesday 13th June 2012
quotequote all
peter tdci said:
If the engines are still running, then it's usually ok! There's also a speed limit below a certain height, so if that was being enforced the change in acceleration would be more noticeable if the aircraft levelled off and maintained its speed at that limit.
Ah yes, that makes sense too, thank you. smile

Super Slo Mo

5,368 posts

197 months

Wednesday 13th June 2012
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It happens a lot out of Heathrow, certainly has done the last few times I've flown from there anyway.


magpie215

4,365 posts

188 months

Wednesday 13th June 2012
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250 kias below 10,000ft iirc

Ari

Original Poster:

19,328 posts

214 months

Wednesday 13th June 2012
quotequote all
magpie215 said:
250 kias below 10,000ft iirc
I don't know what that means... confused

magpie215

4,365 posts

188 months

Wednesday 13th June 2012
quotequote all
Ari said:
magpie215 said:
250 kias below 10,000ft iirc
I don't know what that means... confused
250 knots indicated airspeed when below 10,000 feet

Ari

Original Poster:

19,328 posts

214 months

Thursday 14th June 2012
quotequote all
Ah, ok. Is that a noise reduction thing?

Super Slo Mo

5,368 posts

197 months

Thursday 14th June 2012
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Probably more to do with drag and fuel efficiency, the air gets less dense the higher you fly. However, might be something Heathrow specific.

jontysafe

2,350 posts

177 months

Thursday 14th June 2012
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Incredibly rare in busy air space to have a single stage climb rate, to the uninitiated it can feel disconcerting, but it`s only a reduction in climb or being held at a certain height until ATC says different. A lot of it can also be pilot skill, a gentle roll off the throttles or an abrubt rollback.

FuzzyLogic

1,636 posts

237 months

Thursday 14th June 2012
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Ari said:
Ah, ok. Is that a noise reduction thing?
No, its actually a legal requirement to remain below 250kts in certain (not all) classes of airspace. There are several classes of airspace which have different requirements with regards to allowed traffic / speeds / type of service provided etc.

HTH

RichB

51,383 posts

283 months

Thursday 14th June 2012
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They've been doing this whenever I've flown out of LHR ever since I can remember...

bennyboydurham

1,617 posts

173 months

Thursday 14th June 2012
quotequote all
You'll have been on a SID, or Standard Instrument Departure. In essence, these are standard routings to get traffic from the departure runway to the point at which they continue the journey under their own navigation. Imagine them as slip roads in the sky to the motorway entry point. So, let's say the first point on your flight plan is the navigation beacon at Midhurst VOR in Sussex. Your pilot will be assigned one of the following four SIDs according to whichever runway is in use, punch that into the flight management computer and then after takeoff follow that track, climbing to the heights either as per the chart (3000, 4000 and 6000 feet in the case of the MID4F SID off runway 27R) or will receive instructions from ATC giving him headings and altitudes which over-ride those on the chart. When your pilot gets to the MID beacon he'll be told by ATC to 'resume own navigation' which means the aircraft is cleared along the series of beacons and waypoints that make up the route and will no longer receive directions from ATC, apart from altitude restrictions for other traffic.
In reality aircraft usually fly the first part of the SID and then are given vectors (directions) by ATC. Smaller airfields don't use SIDs at all, and simply direct traffic out away from the airport via radar coverage.



bennyboydurham

1,617 posts

173 months

Thursday 14th June 2012
quotequote all
FuzzyLogic said:
No, its actually a legal requirement to remain below 250kts in certain (not all) classes of airspace. There are several classes of airspace which have different requirements with regards to allowed traffic / speeds / type of service provided etc.

HTH
That's the one. Exceptions are heavy 747s, A380s and the like which would struggle to climb without flaps at 250 knots are given a dispensation and at quiet times the 250 knot rule is waived. Many carriers impose speed restrictions anyhow to prevent more damage in a bird strike, which is much likelier below 10,000 than above.

Ari

Original Poster:

19,328 posts

214 months

Friday 15th June 2012
quotequote all
bennyboydurham said:
You'll have been on a SID, or Standard Instrument Departure. In essence, these are standard routings to get traffic from the departure runway to the point at which they continue the journey under their own navigation. Imagine them as slip roads in the sky to the motorway entry point. So, let's say the first point on your flight plan is the navigation beacon at Midhurst VOR in Sussex. Your pilot will be assigned one of the following four SIDs according to whichever runway is in use, punch that into the flight management computer and then after takeoff follow that track, climbing to the heights either as per the chart (3000, 4000 and 6000 feet in the case of the MID4F SID off runway 27R) or will receive instructions from ATC giving him headings and altitudes which over-ride those on the chart. When your pilot gets to the MID beacon he'll be told by ATC to 'resume own navigation' which means the aircraft is cleared along the series of beacons and waypoints that make up the route and will no longer receive directions from ATC, apart from altitude restrictions for other traffic.
In reality aircraft usually fly the first part of the SID and then are given vectors (directions) by ATC. Smaller airfields don't use SIDs at all, and simply direct traffic out away from the airport via radar coverage.

Could you be a little more comprehensive please? biggrin

That's brilliant, and very interesting, thank you for that. smile

bennyboydurham

1,617 posts

173 months

Friday 15th June 2012
quotequote all
Ari said:
Could you be a little more comprehensive please? biggrin

That's brilliant, and very interesting, thank you for that. smile
You're quite welcome. I must also add that I am not a pilot (well I was a Private one, but that doesn't count) but I do spend too much time flying 737s around in Flight Simulator.