View Full Version : IRS alignment B737NG
Life on top
4th Jan 2017, 15:16
Hello,
In my company we only fly B737NG. We are aligning the IRS' on every turnaround, but wonders if this might be an unneccecary procedure from the past. Is this neccecary on the NG, and is it common amongst other NG operators?
FlyingStone
4th Jan 2017, 15:23
Depends on where you fly, but in Europe with very reliable and accurate VOR/DME/DME updates and dual GPS, it's not really required to align it before every flight.
Nevertheless, I believe it is still Boeing recommendation, "if time permits".
Are you talking of full or fast align every turn round?
Flying Wild
5th Jan 2017, 09:27
SOP at my outfit is for full alignment on turnaround as per Boeing, this despite being fitted with dual GPS.
I would pose the question of when would you ever NOT have the time for a full alignment to be completed on a turnaround?
Jonnyknoxville
5th Jan 2017, 11:39
In Europe anyway , there is no need for any sort of alignment on a turnaround , occasionally you will get IRS/POS disagree warning on the FMC , a fast align sorts this .
Based in central europe, we did a full realignment every turn around until the last 737 left our fleet two weeks ago.
repulo
5th Jan 2017, 15:34
The alignment requirement has its roots by Boeing harmonising the Classic with the NG and other Boeing type aircraft.
When my outfit first received the NG in 1999 we did not realigne at all. As far as I know 757 and 767 also realigne after every flight.
Over many companies, B757/767 733/737/738. In Europe it was a full align before 1st flight, then fast align on turnarounds. Before an ETOPS or long-haul sector it was full align. In a B738 company, new to type, they did full aligns every turnaround. Then a Boeing visit came and they asked, why? After that it became full align on crew changes and fast align on turn-rounds.
Flying Wild
5th Jan 2017, 18:51
SOP at my outfit is for full alignment on turnaround as per Boeing, this despite being fitted with dual GPS.
I would pose the question of when would you ever NOT have the time for a full alignment to be completed on a turnaround?
Having said that, having received the latest batch of NGs, they've got a Honeywell ADIRU issue which means that once initialised at the start of the day, they are left in NAV until the end of the day unless they are likely to have been operating for longer than 18 hours.
BluSdUp
5th Jan 2017, 21:32
A bigger European LCC does not do ANY align on quick turn ( 25 min std).
Do Yourself a favor and check drift by selecting position of L /R IRS and do a quicky if needed. Seen lots of FOs intending to depart with a good spread for a 4hr trip . last hrs over water.
Used to loose one point on a linecheck if you didnt.
Now some cadets dont know how its done.
Charming!!