I assume you mean making reference to it while airborne rather than being on the ground at LHR!

Some of the hospital flights that sometimes come in and out with organs are little light props. Perhaps cherokee was a little too far down the scale ;)

The reason not all can receive it is because 121.935MHz is a 8.33kHz spaced frequency and, IIRC, carriage of 8.33kHz equipment is only mandatory in UK above FL195.


JD
:)

KLM F50s (or have they been modified?) and some helicopters are not 8.33 equipped....I believe it was the rotary winged types ST was referring to.

Firstly totally agree that QNH passed by ATC is a mandatory readback.

If I call to get a clearance prior to start/pushback and advise I have "Info X" why do I need to state the QNH since this is normally passed again when I call for taxi and the readback is mandatory?

If I am inbound (on a Flight Level) I will be passed QNH when cleared to descend to an altitude and this also requires a mandatory readback so why do I need on initial call to pass QNH?

I guess it depends on the unit - at LHR, QNH is not passed by GMC as you taxi, there wouldn't be the RT space most of the time!

Regardless of the QNH issue, I have lost track of the number of times that crews state the current ATIS and have ignored half of it by calling the wrong freq, or asking for Pre departure clearance when the ATIS says it isn't available, or...... I could go on. From our end it often appears crews only wait for the letter then stop listening.

Surely it can't be too hard to acknowledge the letter, QNH, aircraft type and stand on first call to GMP. It certainly saves R/T when we don't have to go back and ask for it all again.

fireflybob, with the greatest respect ;), this is not the original question on the thread - and I don't think anyone is disputing this point - however ...
... this is precisely the thread question (to which, incidentally, there has not yet been offered a satisfactory answer) and ...

... this is a related and very valid point, with which I would totally agree. :ok:

As I have said, there is just too much unnecessary time-wasting double-speak.


JD
:)

JD and fireflybob...

That's a moot point, because at LHR we do not give the QNH out at all, either with pushback or taxi.....if you state the correct QNH first time 'round.

The reason? So we can ensure you have the correct QNH. I'm having problems understanding what is so difficult to grasp.

Gonzo, I don't frequent LHR these days (but did so in a previous life when people boarded a/c wearing suits!) but if you come north of Watford you'll find that at certain unmentioned airports, depending who's on duty, we get the QNH rammed down our throats several times even when it hasn't changed or we give it on initial call with ATIS X only to have it given to us yet again! Am all for safety and anything that avoids CFIT and/or Altitude Bust is a good thing but if you cry wolf too often it loses it's effectiveness!

My dear Gonzo, this is rather in danger of becoming chicken-and-egg.

It is indeed to your credit at LL that you do not repeat the QNH ad infinitum during our push/start/taxy phase, as others such as fireflybob have to suffer elsewhere. At least you accept that one QNH acknowledgement is sufficient. However, this is not quite the original thread question, which was concerned with why we are asked to acknowledge both the ATIS letter and also to repeat the QNH, which is itself an essential and integral part of the ATIS that we are implicitly acknowledging as having copied and understood. One confirmation of QNH, either explicit or implicit, should suffice.

To a professional, such repetition can be irritating as it is clearly unnecessary R/T clutter; in the same way, I'm sure that you would find it tiresome if we were to be constantly asking you for the QNH during taxy, just in case it had changed. Only in the case where QNH does change from the acknowledged ATIS letter should it need to be mentioned (by you) - and then, of course, it will be read back.

Does that help you to grasp the problem? ... or have I missed the point of your frustration ... ?


JD
:)

As a bystander watching with interest can I make a quick comment.

Fireflybob said:
In this circumstance I assume that you would have already listened to the current ATIS, containing the QNH, prior to contacting the APP controller; you may even have been asked to indicate which version you are working with upon first contact.
No explicit QNH readback would be required until you are instructed to descend to altitude since you will not need to USE the current QNH information until that time.

Jumbo Driver said:
I agree that you are acknowledging receipt of the current ATIS, as is the arriving pilot contacting an Approach unit for the first time.
However, controllers need to be assured that departures are working to the same datum as other inbound traffic that has been required to readback the QNH upon descent to altitude.

If you will; you are 'climbing' to field elevation and need to be informed and acknowledge explicit receipt of that information.

Both situations attempt to trap human factor errors (1012/1021) on the communication side.

Jumbo Driver said:
As another poster pointed out; updates once you are talking to GMC or AIR would be transmitted as a broadcast, trusting that you are concentrating upon the job at hand.

Sorry to intrude.
:O

JD,

Why is is that when a flight crew is given a climb/descend instruction, the new level is cross checked between pilots?

Why is it that when a new pressure setting is given, the new setting is cross checked between pilots?

Surely you're both intelligent, resourceful, highly trained people, who would not get it wrong? Surely the handling pilot can be assumed to have heard and entered the correct informtation....Waste of time this cross checking lark, isn't it?

;)

Ooohhh, Gonzo ... you are a card ... ;)


JD
:)

mocoman, thank you for your input ... we are in danger of becoming mired in this one, so I will only respond to one point. You say

This of course is an admirable aim, but I would argue that simple repetition is inappropriate and hardly likely to be effective. Firstly, an error is highly unlikely when departing, as any professional worth his salt is going to set the QNH and then check that airfield elevation is correctly displayed, within normal altimeter tolerances. That should take care of any significant (i.e. transpositional) errors which could cause, say, an altitude bust. Smaller errors of 1mb (27' at msl) or so, if they occur, are actually insignificant and not likely to cause such a problem. Secondly, when arriving, as fireflybob has most eloquently said, the initial descent clearance to an altitude is always given together with the QNH, which of course is read back at that time; no additional readback of the QNH is required when acknowledging the arrival ATIS.

Anyway, I digress; the thread topic concerns the unnecessary repetition of QNH with ATIS acknowledgement and I remain totally unconvinced that this particular procedure actually serves to improve safety.


JD
:)

Agreed, so why do so many pilots "volunteer" the QNH when acknowledging the arrival ATIS?

Reading back the QNH with the ATIS letter is the only check that LHR ATC have to ensure that you have copied/heard the ATIS QNH correctly.

In probably the busiest time in the cockpit, (emergencies aside), it could be rather simple to be distracted and mishear or write down the wrong QNH. By transmitting it in the manner that LHR require you to do, you have an independant cross check.

Independant cross checks are part and parcel of aviation. This one makes sense because as Gonzo states, it is the only time, if you state the correct QNH, that you will hear it at LHR.

It's not a difficult concept to grasp, it's not a time consuming thing to do, and it does have an added safety benefit. Maybe only one crew per year will get the QNH wrong, but if they can be corrected before getting airborne, then surely this check is worth it?

Lack of professionalism by the OP is what we should be stamping out!

You read the QNH back because it is a mandatory readback - as are various other items in a clearance.
How difficult is it really? 4 numbers?:confused:
You know then that you have the correct QNH as do I.

I frankly don't care how important you think you are on your flight deck - I, too, won't give you start up until you've managed to readback the QNH properly.:p

louby

There's a surprise :rolleyes:

Presumably you can now add QNH readbacks to your ever growing list of ATC procedures that you believe are a waste of time. Filed right under "ROCAS" no doubt.

Oh, and just to show that I do have a mind of my own, I completely agree on the point of not passing the QNH to XXX director on arrival...really doesn't bother me if you do or don't as you will get it when you get descent to an altitude.

As many have stated before the tower need to check you have the correct QNH it doesn't take long and it's safety critical. LL check once and that's all that's required.

We need to hear the QNH because it's the rules, simple as that. You want it changed, contact the CAA.

Regarding unneccesary RT it does work the other way. I hail from the LL radar environment and on first contact a/c should pass cleared level, a/c type (yes this is important as I've lost count of the number of incorrectly filed plans, including a few vortex changes!) and ATIS letter.

Now it has become common practice recently for some crews to also include the QNH on first contact with LL director. Why? It doesn't bother me, but 99.99% of the time the a/c is direct to the holding point cleared to a flight level not an altitude. I'll inform the a/c of the QNH when I descend it to an altitude there is no reason for the crew to tell me what it is when they're still at flight levels. Another midly irritating thing is when an a/c is cleared to succesively lower altitudes and continues to read the QNH back with every successive clearance, even though they've read it back correctly once already.

I fear unnecessary R/T loading is a crime committed on both sides of the radio. We need to minimise it without removing the safety nets.