Big jet limited (partial) panel

[bookworm]

Does anyone ever practise flying big jets without an attitude indicator? Or is it sufficiently difficult (or deemed a possibility so remote) that it's not worth it?

[Notso Fantastic]

It is a failure deemed so unlikely it is not needed. The traditional 2 main vertical gyros plus one standby Artificial Horizon have marched off into the sunset. Aircraft are now fitted with CRT/Liquid Crystal screens integrating data from 2 Flight Management Sustems which utilise attitude & position information from 3 Inertial Reference systems. Even the standby horizon is not needed now. On each pilots Primary Flight Display, he can choose between 3 Attitude References from their individual Inertial systems (all independently battery backed-up as well). If you lose all three, you might as well give up. There is no point trying to give more redundancy- better to work on improving other areas, so there is no point training no attitude information scenarios!

[411A]

Ah, look at Notso, the certification expert.

Hey there, IF the standby attitude indicator is "not needed now"....why are so many aeroplanes still fitted with one, right from the factory?
Standing by for the Notso words of wisdom.

bookworm,
At one time, long before Notso's time I suspect, it was indeed a requirement for this to be included in the training for the FAA aircraft rating.

[BlueEagle]

On the B747-400, due to the level of system redundancy and independence, it is allowed, by some authorities, to despatch without a serviceable standby attitude indicator.

We were never expected to practice limited panel exercises.

[bookworm]

Thanks for the input so far. OK, let me change the tack slightly. Would it be reasonable to expect to maintain control without attitude information, or are there aspects of jet handling that mean that what is a standard exercise for lighter aircraft would be all but impossible on a big jet?

[Tinstaafl]

The limited panel light a/c vs. transport a/c situation isn't quite comparable.

Light a/c tend to use a single A.I. and a turn co-ordinator. For redundancy the TC is usually powered independently from the A.I.
Large a/c don't tend to have a T.C. Instead they are equipped with additional A.I.s. & redundant power/data sources.

In the light a/c case the standby system is the T.C. gyro, balance ball & compass to replace the roll information usually provided by the single A.I. Standby pitch information is substituted by interpreting power, IAS & climb/altitude information.

For the large a/c, failure of the primary A.I means reverting to the standby system ie another A.I.

There isn't the same type of 'limited panel' that light a/c have.

Note that a light a/c doesn't have to be fitted with a T.C. It may be fitted with additional A.I.s instead.

[Notso Fantastic]

Well there goes the neighbourhood! To keep to the subject, there are 3 independent attitude references (references , not necessarily indicators). Each of the pilots has his own independent Primary Flight Display CRT and Navigation display CRT. The Primary Flight Display can be switched over to the former Navigation display in the event of failure of the screen. Any of the three attitude references can be switched to the Primary Flight Display for attitude information. This gives so much redundancy that a traditional back up standby third attitude display is really not needed or necessary (though supplied to keep people happy).

As to partial panel training, it's not required. Most pilots have done it on other types early in their careers- enough I would think. I don't believe big jets present any additional problems over smaller types.

These are the opinions of Notso. No doubt having been through with a toothcomb, a bore like 411A will jump to disagree with it somewhere. Sad sad man!

[bookworm]

Thanks again for the info folks.

Tinstaafl, yes, point taken. I suppose I was thinking of a classic jet with steam driven gauges with separate flight instruments. With EFIS and the kit behind it, presumably the EFIS either works with the AI included or it doesn't work at all, in which case the backup is an AI rather than a TC.

Indeed you don't have to have a separate TC in a light aircraft, though you do have to have a slip ball. Our light twin came to us with a single vacuum AI and an autopilot driven by it, with an electric TC. We toyed with the idea of installing a backup electric AI, but ended up with a second vacuum AI and an autopilot driven from the TC. That gives an interesting level of redundancy. Even if the vacuum system as a whole fails, at least you have something aboard that is competent and current at partial panel. :)

BoxcarWilhomena, yes indeed that was what I was driving at. I would envisage that the handling characteristics of a jet (or even a high performance prop aircraft) make flying without attitude reference extremely challenging -- far more so than the equivalent loss of the AI on a light trainer.

[Tinstaafl]

Hi Bookworm,

Even steam driven types still usually used a third A.I. instead of a T.C.

[411A]

Yes indeed, you are right Tinstaafl...now.
But in days gone past, that third attitude indicator was not available, and certainly was NOT when I received my command rating in the B707 years ago, at least on the Boeing aircraft that I operated.
Far too many now fail to realise that the "comforts" they have today are at the expense of those that have gone before.
Ah yes, switch to alternate (or more) sources, but in yesteryear, few and far between.

I wonder how many remember the canyon approach (otherwise known as, rapid descent and pull-up) required for the FAA ATPL, with the primary attitude indicator failed mid-maneuver?

[Tinstaafl]

Point taken, 411.

I was thinking of not-very-pre-EFIS things.

Wonder when the TC was generally replaced by a third AI? 60's? 70's? 80's?

[411A]

Tinstaafl

So far as I know, the B747 was the first US airliner equipped with a standby attitude indicator straight from the factory as standard fit.

The Boeing 707 and Lockheed TriStar offered several switching arrangements for alternate power for attitude/HSI indicators, depending on customer requirements.
For example, some of the 707's that I operated had no alternate source for the F/O's attitude indicator. If the number two radio bus or the number two VG failed, he had no attitude information. PanAmerican and TWA aircraft had more redundant arrangements as I recall due to the much longer overwater sectors that they operated.

Todays pilots in shiny new metal have it too easy...;) :rolleyes: