Confidential Human Factors
Incident Reporting Programme
The Charity
Aviation
Maritime
ATC825
Initial Report
As a commercial pilot I wanted to raise the issue of use of the guard VHF channel (121.50) for practice PANs, generally by GA aircraft. When flying across Europe, as a standard procedure my airline stipulates that we maintain a listening watch on the guard frequency, and rightly so. When this frequency is used by GA users for practice pans it adds to our radio traffic and we are often forced to stop listening/turn down our “box 2” in order to maintain situational awareness and comms on our primary ATC frequency.
My concern is that we therefore often forget to listen in again on the guard frequency after we think the practice PAN has finished, which means we could potentially miss genuine emergencies and attempts to contact us through loss of comms procedures. GA pilots need to be aware that every time they conduct a practice PAN they are being heard by commercial pilots and are blocking the emergency frequency for that time.
I would respectfully suggest that an alternative frequency be assigned and used for practice pans so that 121.50 can be used for genuine emergency and loss of comms situations.
CHIRP Comment
The issue of practice PANs causing problems for those who are required to listen out on Guard is not new and CHIRP has previously sought ways to introduce a training frequency for Practice PANs but this has foundered before because of lack of available frequencies. However, with the advent of 8.33kHz frequency spacing, more frequencies are now available and so there may be scope to address this again. CHIRP has engaged with the CAA and MAA on the possibility of setting up such a frequency but there will undoubtedly be hurdles in the way, not least of which being the cost of setting up the same auto-triangulation facilities that exist with the Guard frequency. We will continue to engage on this issue but would be interested in the views of the community regarding setting up a VHF Practice Emergency Training Frequency (PETF). To what extent are transmissions on Guard a problem? Do those affected report such incidents (or inform ATC that they are ‘off Guard’ due to it being too noisy) and, if not, why not? Current engagement with the CAA and NATS is coloured by the fact that a previous review into this showed few reports of any problems and so a change could not be supported. But a lack of reports is not the same as a lack of a problem and, not that we would advocate this, one wonders what might be the outcome if controllers were also listening on Guard whilst trying to control their own frequency. Ultimately, the number of interceptions of ‘no-comm’ aircraft by air defence units indicates that the turning down of Guard is a real problem and, although a bit simplistic, if only one such interception was prevented then the money saved would probably pay for any change.
Key Issues relating to this report
Dirty Dozen Human Factors
The following ‘Dirty Dozen’ Human Factors elements were a key part of the CHIRP discussions about this report and are intended to provide food for thought when considering aspects that might be pertinent in similar circumstances.
Distraction – other pilots being distracted by calls on Guard.
Communication – potential loss of communication by turning down VHF Guard frequency volume.