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Hendrik13
Topic Author
Posts: 1
Joined: Sat Aug 07, 2021 6:33 pm

long distance at low altitude

Sat Aug 07, 2021 6:56 pm

Hello
just because I am curious.
About less than an hour ago I saw an plane flying at "relative low" altitude flying over Braunschweig Germany.
According to flightradar24 it is a 777 VP-BJP from airline Nordwind flying from Paris to Moscow with 320kt at 9000ft.
What the heck are they doing? What might be the reason for such a strange flight profile? Or is that normal?
cheers
Hendrik
 
gloom
Posts: 580
Joined: Thu Jun 30, 2016 4:24 pm

Re: long distance at low altitude

Sun Aug 08, 2021 6:42 am

Hendrik13 wrote:
About less than an hour ago I saw an plane flying at "relative low" altitude flying over Braunschweig Germany.
According to flightradar24 it is a 777 VP-BJP from airline Nordwind flying from Paris to Moscow with 320kt at 9000ft.
What the heck are they doing? What might be the reason for such a strange flight profile? Or is that normal?


Since it is assumed that 10.000ft is maximum safe altitude for non-pressurized aircraft, I'd assume there was a problem with pressurization. Either unable to fully "close" the airplane, or (more likely) unable to use packs. In any case, it looks like non pax transfer to home base for repairs.

Cheers,
Adam
 
N1120A
Posts: 26927
Joined: Sun Dec 14, 2003 5:40 pm

Re: long distance at low altitude

Sun Aug 08, 2021 6:43 am

My guess is they had a pressurization issue and flew it back to Moscow at the highest eastbound altitude they were allowed to by their op spec
 
N1120A
Posts: 26927
Joined: Sun Dec 14, 2003 5:40 pm

Re: long distance at low altitude

Sun Aug 08, 2021 6:48 am

gloom wrote:
Hendrik13 wrote:
About less than an hour ago I saw an plane flying at "relative low" altitude flying over Braunschweig Germany.
According to flightradar24 it is a 777 VP-BJP from airline Nordwind flying from Paris to Moscow with 320kt at 9000ft.
What the heck are they doing? What might be the reason for such a strange flight profile? Or is that normal?


Since it is assumed that 10.000ft is maximum safe altitude for non-pressurized aircraft, I'd assume there was a problem with pressurization. Either unable to fully "close" the airplane, or (more likely) unable to use packs. In any case, it looks like non pax transfer to home base for repairs.

Cheers,
Adam


10,000 feet is not the assumed maximum safe altitude for non-pressurized aircraft.
 
Woodreau
Posts: 2173
Joined: Mon Sep 24, 2001 6:44 am

Re: long distance at low altitude

Sun Aug 08, 2021 4:20 pm

320kts at 9000ft is not high speed. An indicated airspeed of 250kts results in a true airspeed of around 300kts.
 
gloom
Posts: 580
Joined: Thu Jun 30, 2016 4:24 pm

Re: long distance at low altitude

Sun Aug 08, 2021 4:45 pm

N1120A wrote:
10,000 feet is not the assumed maximum safe altitude for non-pressurized aircraft.


Depends on context. On unpressurized aircraft, usually above 10.000 ft pilot needs to use oxygen, at least according to FAA (and I think it's also a consensus across the world).
https://www.faa.gov/pilots/safety/pilot ... ipment.pdf

So, perhaps wrong wording, still 10.000 ft is the limit on certain conditions. 9000 on the given flight allows a flight without masks on.

Cheers,
Adam
 
N1120A
Posts: 26927
Joined: Sun Dec 14, 2003 5:40 pm

Re: long distance at low altitude

Sun Aug 08, 2021 5:36 pm

gloom wrote:
N1120A wrote:
10,000 feet is not the assumed maximum safe altitude for non-pressurized aircraft.


Depends on context. On unpressurized aircraft, usually above 10.000 ft pilot needs to use oxygen, at least according to FAA (and I think it's also a consensus across the world).
https://www.faa.gov/pilots/safety/pilot ... ipment.pdf

So, perhaps wrong wording, still 10.000 ft is the limit on certain conditions. 9000 on the given flight allows a flight without masks on.

Cheers,
Adam


The FAA allows flight crews to fly up to 12499' in unpressurized aircraft without supplemental oxygen, and from 12500-14500 for 30 minutes or less without supplemental oxygen. There are other standards in other countries.

That said, it is perfectly safe to fly an unpressurized aircraft above said altitudes, just supplemental oxygen is needed.
 
gloom
Posts: 580
Joined: Thu Jun 30, 2016 4:24 pm

Re: long distance at low altitude

Sun Aug 08, 2021 6:18 pm

N1120A wrote:
The FAA allows flight crews to fly up to 12499' in unpressurized aircraft without supplemental oxygen,


Sec. 135.89 Pilot requirements: Use of Oxygen.
(a) Unpressurized aircraft. Each pilot of an unpressurized aircraft shall use oxygen
continuously when flying—
(1) At altitudes above 10,000 feet through 12,000 feet MSL for that part of the flight at
those altitudes that is of more than 30 minutes duration; and
(2) Above 12,000 feet MSL.


There's a mismatch with 91.211, specifying requirements for supplemental oxygen situations, 91.211 seems more general, and targeted on pressurized aircraft unable to maintain pressurization.

However, this is just my opinion, and safe(r) interpretation to both sections cited above.

Cheers,
Adam

PS. General rules from JAR OPS 1, which I believe is used by EASA:
CAR–OPS 1.385 Use of supplemental oxygen
A commander shall ensure that flight crew members engaged in performing duties essential to the
safe operation of an aeroplane in flight use supplemental oxygen continuously whenever cabin
altitude exceeds 10 000 ft for a period in excess of 30 minutes and whenever the cabin altitude
exceeds 13 000 ft.
 
User avatar
zeke
Posts: 16440
Joined: Thu Dec 14, 2006 1:42 pm

Re: long distance at low altitude

Sun Aug 08, 2021 8:41 pm

Hendrik13 wrote:
Hello
just because I am curious.
About less than an hour ago I saw an plane flying at "relative low" altitude flying over Braunschweig Germany.
According to flightradar24 it is a 777 VP-BJP from airline Nordwind flying from Paris to Moscow with 320kt at 9000ft.
What the heck are they doing? What might be the reason for such a strange flight profile? Or is that normal?
cheers
Hendrik


A possibility is it got damaged by ground equipment in Paris during the turn around and the decision was made to ferry it back home for repairs.
 
VMCA787
Posts: 263
Joined: Fri Sep 04, 2020 9:31 pm

Re: long distance at low altitude

Sun Aug 08, 2021 10:10 pm

If it was damaged, there would be a ferry permit issued by the aircraft manufacturer, in this case Boeing. The 9000 ft limit could be a restriction imposed by Boeing.
 
maps4ltd
Posts: 982
Joined: Tue May 08, 2018 4:48 pm

Re: long distance at low altitude

Sun Aug 08, 2021 10:23 pm

I once observed a Delta A320 fly STL-MSP at 12,000 feet (a passenger flight). May have been a pressurization issue there too.
 
Cubsrule
Posts: 15363
Joined: Sat May 15, 2004 12:13 pm

Re: long distance at low altitude

Mon Aug 09, 2021 12:14 am

N1120A wrote:
My guess is they had a pressurization issue and flew it back to Moscow at the highest eastbound altitude they were allowed to by their op spec


It could also be an issue with the oxygen system; I don’t know what the EASA altitude limit is without it (nor do I know whether the relevant Op Spec permits operating empty above that limit without pax and with relevant oxygen), but there’s almost certainly some altitude limit.
 
ACDC8
Posts: 8032
Joined: Thu Mar 10, 2005 6:56 pm

Re: long distance at low altitude

Tue Aug 10, 2021 12:12 am

Flew from YLW to SEA with QX a few years back on one of their Q400s. Shortly after take off, the pilot came on the PA and said that they were having a pressurization issue so we'd have to fly at a lower altitude until they can resolve it. They eventually fixed it and we continued our climb, was a real shame, was really enjoying the flight until then.
 
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BawliBooch
Posts: 1637
Joined: Mon Nov 28, 2016 4:24 am

Re: long distance at low altitude

Tue Aug 10, 2021 2:24 am

Late 90's. Indian Airlines A320 from BKK to DEL via Yangon delayed by 2 hours at BKK because of Technical Fault. Angry passengers were told that there was a fault in the aircraft Aircondition system - i think they meant Pressurisation System.

Aircraft flew at a very low altitude between BKK and Yangon. Further delay at Yangon. Flight continued to DEL after more delay. We were flying under 29K feet for the first half of the flight. Somewhere over Gwalior, there was a "pooffff" sound from the left engine after which we descended to below 10K feet till DEL. There was also a strange grrrr sound from the left engine. We had clearly suffered some Engine problem. Cabin crew were in Full emergency drill mode into DEL with one cabin crew sitting in the aisle seat in the exit row.

Aircraft was a single bogey A320, rare in India at the time. Stickers in the toilet and bulkhead indicated that this was a ex-MyTravel Airways Airbus.
 
teachpdx
Posts: 172
Joined: Wed Jun 28, 2017 1:51 am

Re: long distance at low altitude

Wed Aug 11, 2021 1:43 am

Way back when (2007?) flew UA OKC-DEN on a 735 still decked out in Shuttle livery.
Pushback, then a long, hot wait before pulling back into the gate. Departed 2.5 hours later with an inop pack. I think we topped out at FL240 and went way far south (Austin and El Paso) to get around a dense line of storms we couldn’t climb over. 1 hour scheduled flight was nearly 3, all in. Plus the departure delay, definitely missed the last connecting flight of the night.

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