View Full Version : Too low air pressure to fly
SpotOn_No
10th Feb 2020, 07:26
Norwegian Carrier Widerøe has had to cancel several flights in the northern part of Norway today due to air pressure being below 946 hPa - which apparently is the certification limit for some of their aircraft (WF fleet consists mainly of DHC-8 variants).
Not a very common occurrence....
Unfortunately I'm not allowed to post URLs or pictures yet, but you can find the story at the website of the Norwegian national broadcaster NRK (.no).
atakacs
10th Feb 2020, 19:05
Sounds a bit wierd. That would mean they could not operated any mid to high altitude Airport?!
eckhard
10th Feb 2020, 19:32
Perhaps they can’t set anything below 950 on their altimeters?
Dan Dare
10th Feb 2020, 19:48
What about QNE?
SimCaptain
10th Feb 2020, 20:00
Low Pressure Grounds Widerøe's Dash 8 Fleet (https://simpleflying.com/low-pressure-grounds-wideroes-dash-8-fleet/) due to storm "Ciara"...
atakacs
10th Feb 2020, 20:13
already here (https://www.pprune.org/tech-log/629618-too-low-air-pressure-fly.html)
go-around flap 15
10th Feb 2020, 20:37
Reminds me of a particularly long and boring flight a while back where I was finding out what the lowest QNH you can forecast on the 737 FMC by trial and error - not that I can remember the number anymore! Like I said, was very bored.
SpotOn_No
10th Feb 2020, 20:50
Perhaps they can’t set anything below 950 on their altimeters?
Close. Apparently, the lowest setting possible was 948.
eckhard
10th Feb 2020, 21:32
What about QNE?
Indeed! Bit of a lost art? Modern glass equipment can set very low and high figures on the sub-scale, which makes QNE unnecessary. QNE didn’t figure in the Ops Manuals of my airlines in the last 25 or so years.
Alpine Flyer
14th Feb 2020, 19:23
What about QNE?
You'd need a QNE minimum as well.
FAA AIM recommends not to operate when you can't adjust to low pressure (and once more impressed by how the FAA manages to produce useful information in readable form, an art totally lost to EASA).7.5.2 Low Barometric Pressure
When abnormally low barometric pressure conditions occur (below 28.00), flight operations by aircraft unable to set the actual altimeter setting are not recommended.
NOTE-
The true altitude of the aircraft is lower than the indicated altitude if the pilot is unable to set the actual altimeter setting.