Standby Attitude Indicator ILS
 

Hello Gents, are standby attitude indicators on transport category jet aircraft in FAA land required to have an ILS presentation on the actual instrument itself?
The ability to navigate an ILS with nothing but standby instruments? Aircraft in question is B737 Classic.

I am not aware of any requirement to have any sort of standby ILS indicator. Acceptable redundancy is typically provided by independent left and right side instruments, radios, and associated source selection capability. I don't recall that any of the part 25 aircraft I worked on had a standby display of ILS Loc and GS deviation.

All the bizz jets I’ve operated have selectable ILS indications on their IESI.

Ours had the LLZ and GP needles (not FD's). Ex-Sabena ships, all mechanical. Both steam-gauge and EIS configured.

Back when the 737 was introduced there were no electronic primary or standby instruments. The standby instruments in those days were typically a mechanical attitude indicator and a separate IAS/Altitude indicator. The same was true when the MD-11 was introduced. At that time Honeywell and DAC believed there was so much system redundancy that no standby instruments were required. In all the Honewell advanced flight decks a PFD and Engine display remain after failure of any 4 of the 6 display units. Standby instruments were fitted because that was easier than arguing with FAA that they were not required.

Modern electronic standby instruments have much more capability but there is a difference between capability and a requirement to have that capability.

Different names because of different features.

FYI the standard ILS minima w/FDs are 550 m, but 720 with the ILS raw indicators.

The OP asked about standby instruments equipped (or not) with ILS indication. I flew one, shared it.

Someone says they had an FD setup, which is not the same on the instrument level. Since we're talking about standby attitude indicators and their add-ons, it seems relevant. You surely know the difference better than I could explain.

To get a standby instrument equipped with predictive steering commands would be a nice engineering trick, yet there must be a reason no one ever installed any such thing.

A "director" is a indication of the required correction and to be followed by whoever is in control.

A "deviation indicator" is an indication of the deviation in a certain point and time and has nothing to do with the correction required. Depending on situation the required correction could be big or small.

They have far from similar functions.

From memory (some can confirm or correct): on B737 classic non efis the standby attitude indicator had standard ILS deviation indicators (NAV 1). The B737 classis EFIS has standard ILS deviation indicators on the standby (NAV 1) if the captain EFIS is not connected to standby power. The B737 classic EFIS with captain EFIS on standby power has standby attitude indicators with the ILS deviation indicators (NAV 1) as an option.

Some people actually like this as the standby deviation indicators had a tendency to "come alive" slightly earlier than on the EFIS which sometimes helped to anticipate the turn on the localiser in raw data flying.

The standby instruments shown in this image look similar to the ones used by Douglas. Does the pictured standby attitude indicator display GS and LOC dev? I see no scales, pointers, or flags.

http://www.b737.org.uk/images/centrepanel.jpg

In my old paper FCOM of the classic it shows the standby horizon with an approach mode selector (customer option) which was a three position switch with OFF, ILS, B/CRS as available options. In ILS mode it would show the GS and LOC pointer in front of the horizon ball and aircraft symbol. Not a FD, just a normal ILS cross pointer. And a LOC and G/S flag in case either of those did not work or receive. It worked solely off the No. 1 ILS receiver.

70 Mustang

Glideslope and localizer, aka "raw data." They show only your angular deviations from the horizontal and vertical perfect positions. If you're right of course see a "fly left" needle, it's up to you to turn left just the right amount, then level the wings, then turn right at just the right time and just the right amount, so you re-intercept the course without blowing through it. If you see "fly left" and simply turn left until it's centered, you're virtually guaranteed to blow left through the course at a severe angle. Shown as a pair of needles over the DG on old simple planes (think 1970's 172), or (on a HSI) the middle split out part of the course needle (for the localizer, same as the VOR course function) and diamond or triangle on one (or both) side(s) moving up and down (for the glideslope.) On standby ADI's that have it, pair of needles over the standby ADI. Probably never over a main ADI.

Flight Director. Tells you to fly left/right, or up/down, but with none of the planning and finesse required by the raw data. The computer does your thinking for you. If you're right of course and see a "fly left," you can follow it stupid as a monkey, and it will show a fly-left to guide you into the initial left bank, then show centered when you should level your wings, and show a fly-right to guide you into a bank to the right to make a perfect intercept. Shown as either a pair of needles, or an upside down V shape for you to slot a triangle into, over the main ADI. Probably never in the history of aviation shown over a standby ADI.

EXDAC

As mentioned before, in this case, in flight with loss of both engine driven generators (so automatic revertion to standby power), the captain would retain his EFIS indications so there is no need for a NAV 1 indication. It is an option.

Keep in mind the original purpose of the standby ADI was specifically to be the "Umpire." In other words,if one of the two normal ADI's failed or gave suspected erroneous attitude information, an instant time critical comparison was readily available between the standby ADI and the two normal ADI's. In turn, this hopefully would confirm which of the normal ADI's was suspect. Two against one.
Later, adding ILS information to the Standby ADI was icing on the cake. As BraceBrace has mentioned in his post, the earlier first inbound movement of the Localiser on the Standby compared to the old fashioned HSI display and associated FD on the main ADI's was a useful hint that you were closing in on the Localiser.

With loss of all generators in some of the 737 Classics, and thus loss of power to both normal ADI's, that left the pilot with (among other instruments) only the standby ADI which worked off the aircraft battery. That had 30 minutes if you were lucky. Instrument flying using only the Standby ADI really sorted the men from the boys. A skill now universally lost forever for some pilots.

There is a lot of very good opinion here, but it is just that; Opinion. To get the answer to your question you need to refer to FAR Part 25 which is the certification requirement.

Perhaps only in MEL? 34-7
 

https://cimg7.ibsrv.net/gimg/pprune....ba78575987.png

https://cimg0.ibsrv.net/gimg/pprune....4d0eccca2.jpeg

Part-25 does not say anything about navigation equipment, as that relates to the type of operation rather than airworthiness. If you look in 121.349 for FAA and AMC2 CAT.IDE.A.345 for EASA, you find that in fact only one ILS receiver is needed. And there is no reference to any requirement to have it displayed on the standby attitude. Which is just as well, since there are plenty of Part25 aircraft flying around out there with older standby instruments that have no such display. It's just Mr. Boeing being nice to you!

Bizjetjock is correct. You need to look at the airspace requirements, you could fly VFR only but who would dispatch an acft VFR only...

Possibly not VFR. I’d think that’d be too limiting. I could see the MEL saying day VMC only though.

Could you provide a reference?