So we have the option to use the steam gauge standby instruments or the ISFD in the NGX.From what I learned, the ISFDs showed up around 2003 and are now delivered with all newer NG aircraft.What I'd like to know is whether there is a significant tendency among airlines to replace the analog standby instruments in already delivered/older NGs with ISFDs or if the analog gauges are considered good enough in most cases.Maybe someone with real-world experience could comment on this.Thanks

I doubt the benefits of retrofitting would be worth the cost, but perhaps there are some airlines that have decided otherwise. Especially in today's economic climate airlines aren't going to spend any money on a modification that does not come with a clear benefit.John-Alan Pascoe

I doubt the benefits of retrofitting would be worth the cost, but perhaps there are some airlines that have decided otherwise. Especially in today's economic climate airlines aren't going to spend any money on a modification that does not come with a clear benefit.John-Alan Pascoe

That's what I would think too. But maybe there is a compelling reason to upgrade the standby system which I can't see at the moment ...

Presumably there is some kind of benefit or Boeing wouldn't have made the design change in the first place. Whether that benefit is great enough to justify the cost of retro-fitting an existing aircraft is a different matter.Possible benefits would be: 1. Safety, I doubt that the safety benefit of the ISFD is substantial though. 2. Maintenance / Reliability. I also doubt the IFSD is significantly more reliable / requires significantly less maintenance, but if I'm wrong about that it could be a compelling reason.John-Alan Pascoe

I'd agree. It seems that the PMDG community is fixated on fail operational autolands in the 737. The RW airlines are not and don't have enough incentive to be.

Our planes had the ISFD so I cannot tell you if the old systems are provisioned for the upgrade.However, modifying the aircraft to te new ISFD is a bit different than replacing only the indicators.ISFD has its own battery charger in the electrical compartment, and needs input from the ADIRU for heading information.The analog ones has:Stby attitude indicator: power, light, ILS signalStby Altimeter: ligth, instrument vibrationThe ISFD needs: Power from its battery pack, wich is powered by the overhead electrical meter panel, ils data, adiru data.So, there is a bit of wiring modification to be done from the overhead to the e/e compartment, to the flight deck assuming there is no factory provisioning for it.About the "old style" indicators I can tell you that the altimeter is very bad speaking about precision.On the classics I tested about every stby altimeter in the fleet, and it was not unusual to find great errors in the indications.Errors reaching 7/800 ft with vibration and passing 1000ft without vibration (I replaced them very often in the latest years).The digital ones are pretty relaiable and the errors are very small compared to the old ones.

I fly in a RW CRJ fleet that has both analog and ISFD gauges. It's a lot like the replacement policy with our newer FMS heads, and cockpit seats: they use whatever they have in the shop to get the job done. They buy new parts to replenish what is installed from the shop with more regard to the bottom line than anything else. It takes RW airlines a LONG time to upgrade anything. The old system worked, and the old system is now cheaper because of the new system.Just my two cents, free of charge for a limited time.

I believe ISFD is a bit different from Honeywell/Collins MCP in that it is an option, whereas MCPs were just changed. FWIW, even last year, there were at least some NGs delivered factory-fresh with analogue stand-by.

 

I'd agree. It seems that the PMDG community is fixated on fail operational autolands in the 737. The RW airlines are not and don't have enough incentive to be.

For my part, I'm not really obsessed regarding autoland. I tested it once to make sure that I know how it works, and I use it for CATIII approaches and whenever the use of autoland is mandatory.Other than that, I hand-fly all approaches and landings.

I believe ISFD is a bit different from Honeywell/Collins MCP in that it is an option, whereas MCPs were just changed. FWIW, even last year, there were at least some NGs delivered factory-fresh with analogue stand-by.

Interesting facts. Thanks.

I'd agree. It seems that the PMDG community is fixated on fail operational autolands in the 737. The RW airlines are not and don't have enough incentive to be.

Had to laugh reading this. My thoughts exactly!

Just some input, all of SWA's brand-new airplanes still come with the analogue standby gauges. I also think it has to do with fleet commonality, so you don't have a fleet with mixed gauges. Even though it wouldn't make much of a difference in a pilots eyes, it would cause a logistics problem with different replacement parts for different planes, etc..