Automated FL bust detection?
 

Airbus have issued an FCOM revision advising that the selected altitude transmitted to the ground based ATC will include the wrong QNH when the aircraft is above the Transition altitude.

Excuse my ignorance here. This is all news to me.

Obviously our actual altitude is transmitted but according to the revision, the selected altitude (eg cleared to FL XX) is also transmitted? Apparently it's for the purpose of automated level busting detection.

What exactly do controllers or the automated equipment see -
Selected altitude & QNH, Actual aircraft altitude & QNH?

Is this ground based ATC/ level busting equipment in use widely?

In the UK Mode S downlinked parameters are currently available to th London and Manchester TMA although it will be rolled out further over he nxt few years.

There are many really quite significant benefits to it's introduction and IMHO the single most important safety benefit is the reduction in undetected level busts before the bust has actually taken place.

I'll no doubt miss off something but according to the settings onboard the a/c, the following can be downlinked and viewed at suitably equipped units:

1 - The serial number of the transponder (this is an improvement over just the squawk as it also enables us to identify a/c that at on A7000 to improve detection and reduction on CAS infringements and tracing action)

2 - IAS

3 - Current Heading

4 - Selected level (SFL)

5 - Actual level

In total there are many many more that have the potential to be downlinked, but these are the main ones. Without doubt the most frequently of benefit is the SFL. It has singularly prevented many many incidents from developing and I wouldn't like to be without it. The primary method of prevention is, and always will be, issuing a safe clearance and receiving an accurate readback, followed by correct action in the cockpit. However we all know that mistakes happen! And although the Mode S data is not always available and at the moment it is a question of whether the controller sees the SFL, it's reassuring how many are caught before they develop.

Further down the line there is the possibility of developing an automated SFL/cleared level check but this would be a few years away. Electronics strips are maybe a stepping stone along the route but also a future hope is that improvements in voice recognition will allow a direct comparison between the clearance issued by the controller with the SFL dialled in the cockpit. But I'd like to reiterate that this is still some way away. For the moment the data is available from most a/c and the manual voluntary check goes a long way to improve safety on a daily basis.

A couple of caveats - this is only the UK perspective, I don't know how far advanced other ANSPs plans are and also I'd like to highlight that QNH is NOT available at any time. It was originally requested but I understand that there were objections from certain countries to this being available - quite why I can not begin to imagine. So this means that we can not detect, and prevent, any incident through incorrect QNH being selected or failure to select 1013 until the level bust has already occurred - what a shame!

Maybe this will be resolved in the future as we see several incidents each year through this......

Anyway, that's my 14p's worth, hope it helps - safe trips....

As Cartman said above.

However it is not an automated level bust detection - it still requires the ATCO to check the SFL on radar. Most times they will, sometimes it is just too busy, or like anything, mistakes will be made and we may rwad what we want to read and not what is actually on the screen (false positive).

Automated checking is one of the benefits that will happen with the introduction of electronic flight progress strips - one of the main reasons that management are pushing the introduction.

Unfortunately management don't seem to realise that the benefits might be outweighed by the detrimental aspects of EFPS versus paper strips - but that is another argument.

As Cartman says, you could have the correct level selected, but the wrong QNH - there is no facility for detection of this.

I e-mailed an engineer a while ago with what I thought was a fairly simple solution for having the wrong pressure selected (considering NATS has some very clever engineers who did wonders with Mode S and Vertical Stack Lists).

Unfortunately he didn't even respond to th ee-mail, never mind actually saying wheteher it would work or not :*

Anotherthing,

Dig out the email and PM it to me, you possibly were advised of the wrong person to send it to. We like new ideas! :ok:


nnc0,

The problem with the Airbus QNH has been know for some time in the Mode S world. However, QNH setting is not one of the DAPS that has been mandated in Europe for Enhanced Surveillance, hence for now none of the NATS systems take any notice of it. In hindsight, it should have been included in the Enhanced Surveillance requirements as it could be used for potential tools to prevent level busts to indicate that the pilot is flying with the wrong QNH setting.....hindsight's great! :E

The Selected Altitude DAP that is displayed to controllers is in effect just a number and is unaffected by any QNH settings, so the fact that Airbus have cocked up their implementation has no impact on current ops.

RS

Thanks very much folks. Great info.

Radarspod and ProM - I have Pm'd you. Don't ridicule my idea too much :ok: