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Before primary flight displays, where were their contents displayed?

Posted: Tue Nov 03, 2020 6:23 pm
by Trimeresurus
The attitude, speed and altitude obviously had their own analog indicators since forever, but what about stall speed, overspeed, AoA, flap speeds, pitch limitations, autopilot modes, flight director etc? For example, a 747 classic vs the 747-400.

Re: Before primary flight displays, where were their contents displayed?

Posted: Tue Nov 03, 2020 7:14 pm
by GalaxyFlyer
None of it was displayed, there were no stall sped, AOA, pitch or roll limits , flap and gear speeds (might have been on a placard) shown—all in the pilot’s head. There were “bugs “ small plastic tabs for V speeds that the pilot manually slide into position. There were separate AP mode displays and master warning, but no EICAS.

Re: Before primary flight displays, where were their contents displayed?

Posted: Tue Nov 03, 2020 8:31 pm
by unimproved
In the placards, QRH and other stacks of paper carried in the cockpit. That's why a classic requires a 3 man crew.

Things like AOA (basic 1 on 1 of what the sensor measures without any stall protection) also had their own gauges.

Re: Before primary flight displays, where were their contents displayed?

Posted: Tue Nov 03, 2020 10:01 pm
by Max Q
It shows how far we’ve come with modern displays that this question is asked but it’s a good one !


On the older aircraft there were quite a number of additional items that had to be committed to memory

Maximum flap extension speeds, gear extension, retraction and extended speeds (yes, all three were different on several types) maximum EGT for start on all engine types across the same aircraft variant, starter limits, yaw damper inop speed / altitude limits are just a few examples

Some of these limits like flap and gear speeds would be displayed on a placard on the instrument panel but that wasn’t of any help when you were being tested on proficiency checks !


FYI, the AOA vanes have been installed in jet transport types for decades but usually have only provided inputs to the stick shaker and pusher if installed


Display of AOA could have been provided via a separate analogue gauge but rarely was, airlines didn’t see a need and weren’t going to pay extra for it

Re: Before primary flight displays, where were their contents displayed?

Posted: Wed Nov 04, 2020 12:31 am
by Starlionblue
A couple of things from your list were indeed displayed by the end of the steam gauge era.

747 Classic airspeed indicator with Vmo needle.
Image

Tristar attitude indicator with servo-driven FD bars.
Image


At the slower speeds of pistons, coloured markings on the face of the airspeed indicator suffice to show speed limits.

Image


GalaxyFlyer wrote:
None of it was displayed, there were no stall sped, AOA, pitch or roll limits , flap and gear speeds (might have been on a placard) shown—all in the pilot’s head. There were “bugs “ small plastic tabs for V speeds that the pilot manually slide into position. There were separate AP mode displays and master warning, but no EICAS.


The introduction of EICAS/ECAM is one of the biggest system changes which happened at the same time as the transition from steam to glass. Instead of a master warning system which just, ahem, warned you, all warnings and cautions are now integrated and presented in a logical manner, with automatic display of actions to be performed, automatic prioritization, sensing of parameters, and so on. This allows much simpler management of non-normal situations, and is probably the main reasons that large airliners could go from three to two crew operation. Not to mention parameter presentation in general, which no longer requires discrete gauges and indicators for every single item.

Flap and gear limits are still placarded right in front of us. :D

Re: Before primary flight displays, where were their contents displayed?

Posted: Wed Nov 04, 2020 8:22 am
by unimproved
Max Q wrote:
Display of AOA could have been provided via a separate analogue gauge but rarely was, airlines didn’t see a need and weren’t going to pay extra for it

I guess we were te exception to that.

But hey, some 747 classics were even upgraded to a basic glass cockpit some years before they were retired.

Re: Before primary flight displays, where were their contents displayed?

Posted: Wed Nov 04, 2020 11:29 am
by Woodreau
It’s unfortunate that AOA isn’t readily available on Airbus (no idea about Boeing) only way I’m aware of to see AOA is to switch to Backup Airspeed mode where the airspeed tape/airspeed indicator is replaced by a fast/slow indicator

A civilian version of the AOA indexer found on military aircraft - well on fighters at least.

From what I understand the military doesn't target airspeed for landing and instead uses the AOA indexer for airspeed control.

Re: Before primary flight displays, where were their contents displayed?

Posted: Wed Nov 04, 2020 3:27 pm
by Starlionblue
Woodreau wrote:
It’s unfortunate that AOA isn’t readily available on Airbus (no idea about Boeing) only way I’m aware of to see AOA is to switch to Backup Airspeed mode where the airspeed tape/airspeed indicator is replaced by a fast/slow indicator

A civilian version of the AOA indexer found on military aircraft - well on fighters at least.

From what I understand the military doesn't target airspeed for landing and instead uses the AOA indexer for airspeed control.


If you switch to flight path angle, the difference between pitch angle and the bird is pretty much AoA.

Re: Before primary flight displays, where were their contents displayed?

Posted: Wed Nov 04, 2020 5:22 pm
by Lemmy
For older jets with INS systems, did it show your track like it would a VOR radial?

Without a visual representation of the flight plan, I suppose you had to be really careful when entering waypoints .. especially when they were in lat/long format.

Re: Before primary flight displays, where were their contents displayed?

Posted: Wed Nov 04, 2020 5:31 pm
by GalaxyFlyer
Your track was shown on the HSI, just like the VOR, but there was no map display. That’s why there are requirements for CFP entries and oceanic plotting.

Re: Before primary flight displays, where were their contents displayed?

Posted: Wed Nov 04, 2020 5:33 pm
by GalaxyFlyer
Woodreau wrote:
It’s unfortunate that AOA isn’t readily available on Airbus (no idea about Boeing) only way I’m aware of to see AOA is to switch to Backup Airspeed mode where the airspeed tape/airspeed indicator is replaced by a fast/slow indicator

A civilian version of the AOA indexer found on military aircraft - well on fighters at least.

From what I understand the military doesn't target airspeed for landing and instead uses the AOA indexer for airspeed control.


Oddly, the Citation had the indexer almost from Day One

Re: Before primary flight displays, where were their contents displayed?

Posted: Wed Nov 04, 2020 6:50 pm
by Woodreau
Starlionblue wrote:
If you switch to flight path angle, the difference between pitch angle and the bird is pretty much AoA.


That may tell you the AOA but how do you know if you are at the correct AOA?

From what I understand you are at the correct alpha when the AOA is on speed (green circle) and not fast or slow (amber arrow)

Re: Before primary flight displays, where were their contents displayed?

Posted: Wed Nov 04, 2020 11:17 pm
by Max Q
unimproved wrote:
Max Q wrote:
Display of AOA could have been provided via a separate analogue gauge but rarely was, airlines didn’t see a need and weren’t going to pay extra for it

I guess we were te exception to that.

But hey, some 747 classics were even upgraded to a basic glass cockpit some years before they were retired.



Interesting


You had a separate AOA gauge on the Classic?

Re: Before primary flight displays, where were their contents displayed?

Posted: Thu Nov 05, 2020 1:06 am
by Starlionblue
Woodreau wrote:
Starlionblue wrote:
If you switch to flight path angle, the difference between pitch angle and the bird is pretty much AoA.


That may tell you the AOA but how do you know if you are at the correct AOA?

From what I understand you are at the correct alpha when the AOA is on speed (green circle) and not fast or slow (amber arrow)


Ah yes. You cannot tell if you are at the correct AoA. I guess pitch and power are close enough for airliners?

The Vls and Alpha Max indications at least indicate the highest acceptable AoA, though they don't tell you it directly.

Re: Before primary flight displays, where were their contents displayed?

Posted: Thu Nov 05, 2020 10:23 am
by flipdewaf
Woodreau wrote:
Starlionblue wrote:
If you switch to flight path angle, the difference between pitch angle and the bird is pretty much AoA.


That may tell you the AOA but how do you know if you are at the correct AOA?

From what I understand you are at the correct alpha when the AOA is on speed (green circle) and not fast or slow (amber arrow)


I would guess there is no 'Correct' AOA as such. If you are going the right speed and and the vertical acceleration is what you want then by default the AoA is correct? a bit like saying how do you know the wheels on your car are the correct angle for going round the corner? You don't but you still make it round the corner.

Fred

Re: Before primary flight displays, where were their contents displayed?

Posted: Thu Nov 05, 2020 12:45 pm
by Flow2706
Woodreau wrote:
It’s unfortunate that AOA isn’t readily available on Airbus (no idea about Boeing) only way I’m aware of to see AOA is to switch to Backup Airspeed mode where the airspeed tape/airspeed indicator is replaced by a fast/slow indicator

A civilian version of the AOA indexer found on military aircraft - well on fighters at least.

From what I understand the military doesn't target airspeed for landing and instead uses the AOA indexer for airspeed control.

Also, from a systems point of view AOA is available through the Alpha Callup function through the AIDS system on the MCDU. It's mostly a maintenance function but it's still quite valuable f.e. in ADR disagree situations.

Re: Before primary flight displays, where were their contents displayed?

Posted: Thu Nov 05, 2020 2:38 pm
by CosmicCruiser
On the -11 we never had AOA until the HUDs were installed. The HUD displayed it in the upper right corner.

Re: Before primary flight displays, where were their contents displayed?

Posted: Thu Nov 05, 2020 3:50 pm
by CRJockey
On the CRJ you can see the AOA on the EICAS "menu" page, where Bombardier chose to collect seemingly random data points together. Quite interesting to train deep stall recovery in the SIM and observe the AOA, but not useful in everyday life.

I wonder however, if AOA being displayed is really that useful in an airliner anyway. I doubt for example, that the AF447 crew would have been able to get around their sheer startling about that the **** happened, with a displayed AOA. But I might be wrong.