Wording question

[blousky]

Hi folks,

Here below you'll find two sentences from our OM. They follow each other and one of them is obviously wrong.
Could a native english speaker tell me which one?

The true meaning of both sentences is: Above a certain altitude the autopilot can be either on or off but below that altitude, it must be off. I.e. the last phase of the approach must be done manually.

But which one says it correctly?

In a single channel ILS approach, the autopilot must be disengaged at or below 140 FT ARTE.
In an approach using V/S mode, the autopilot must be disengaged at or above 300 FT ARTE.

Thanks for your help,

Dan.

[oldchina]

blousky

The first sentence has no meaning in the real world. It says you could disengage the A/P at zero FT.

[FlightPathOBN]

at or above

instead of at or below.....

[FE Hoppy]

More correct to say "must be disengaged no later than xxxft on approach.

[Northbeach]

Just guessing here........

In a single channel ILS approach, the autopilot must be disengaged at or below 140 FT ARTE.
In an approach using V/S mode, the autopilot must be disengaged at or above 300 FT ARTE.

The ILS is a precision approach. The precision approach has the benefit of a glide slope to aide the crew with the descent. This company has a policy for the crew to disconnect the automation at a specific height.

The V/S (Vertical Speed) mode would be used in a non-precision approach (there is no vertical guidance); Localizer, NDB/ADF or VOR. The same company has a policy for the crew to disconnect the automation at a different, and more restrictive, height when flying a non precision approach (V/S mode) than a precision approach (single channel ILS).

Having the pilots disconnect the automation on a non precision approach at a more restrictive height gives them more time to manually take over, establish “feel” and be stabilized. I am just guessing here...........

I do not know the company, the specific reasons or even the type of equipment.

We hardly fly any approach other than the ILS or RNP/RNAV. Occasionally there is the stand alone GPS and rarer still the non-precision approach using something other than LNAV/VNAV.

Hope it helps.

Northbeach

[BOAC]

blousky - how on earth did your OM get past the regulator?

[blousky]

Thanks all of you for your answers. I'll suggest FE Hoppy's wording to my chief.

I can see where the problem comes from. Try to follow as it's subtle.

We can see the word disengage as the action to switch it off. So you have to disengage the autopilot before reaching a certain altitude -> the "at or above" comes from that.

We can also see "disengaged" as the state of the autopilot. It's either on or off. Engaged or disengaged.
For example: at 92ft, the autopilot must be off -> it's disengaged.
So, the at or below is also correct!

Now, having the two sentences in the same paragraph is confusing.

I was told it comes from boeing and I did a little research. For sure I found it! The exact same two sentences in a document from boeing...

I'll have to check on a more official source but this seems to come from them Page 22 Or L.10.10

Now I don't know how our OM passed the regulators but those two phrases passed the FAA ;-)

Now I don't know what to think anymore...

[FlightPathOBN]

its called a 'kludge'

you read it, and know what it means, not what it says....

[BOAC]

I am used to 'Must not remain engaged below xxx'

Two countries separated by a common language?