An initiative has been launched by Maastricht Upper Area Control Centre (MUAC) to relieve frequency congestion and controller work-load.

So far this year, even before the start of the summer season, MUAC has been experiencing a traffic increase that makes ATC sectors and frequencies very busy. We are working proactively to offset the impact of this increased demand in many ways. One of them is trying to save valuable frequency-time that is often lost by stations calling in and overriding each-other’s transmissions.

For which reason we have issued the NOTAMs for the UIRs under MUAC control, valid from 23 March to 12 April 2015, with as body text as follows:

A STANDBY CAMPAIGN AT MAASTRICHT UAC IS CONDUCTED IN ORDER TO REDUCE THE FREQUENCY LOAD AND THE NUMBER OF CROSS-TRANSMISSIONS. THE PHRASEOLOGY ‘STANDBY FOR MAASTRICHT ON (CHANNEL-NAME)’ CAN BE EXPECTED FOR TRANSFER OF FREQUENCY. PILOTS ARE REMINDED TO ANNOUNCE THEY ARE STANDING-BY WHEN FREQUENCY TIME ALLOWS.



Most of all, MUAC would like stations not to call in at all, but after having a close look at ICAO regulations, it is clear this should not be done.

ICAO Doc 4444 - PANS ATM / Chapter 12 – PHRASEOLOGIES § 12.3.1.3
1. STAND BY FOR (unit call sign) (frequency) ;
2. MONITOR (unit call sign) (frequency) ;

So, an aircraft may be requested to:

1. 1.       “STAND BY” on a frequency when it is intended that the ATS unit will initiate communications soon, and to
2. 2.       “MONITOR” a frequency when information is being broadcast thereon (e.g. ATIS).

STAND-BY Phraseology

ATC: “SPEEDBIRD 123, standby for Maastricht (on) 118.950”

Current ICAO regulations (ICAO Annex 2 – Rules of the Air, ICAO Doc 9426 and 7754) require:

• an initial call [from the flight] when entering the area of an ATS unit,  and
• a ground-initiated call to an aircraft prior to its leaving that area.

These are considered to be a minimum requirement for airground communications.

So the Stand-By Phraseology after being transferred in this way should be:

Needless to say that such an announcement could lead to cross-transmissions again, so airstations are kindly requested to wait for a silence on the radio before doing so.

FAQS concerning the NOTAM:

1. Should it not be “Monitor” instead of  “Stand-By”?

No, ICAO Doc 4444 - PANS ATM / Chapter 12 – PHRASEOLOGIES § 12.3.1.3, as quoted above, clearly makes the difference.

2. Does this not increase the risk for a Loss of Communication?

If the air station makes an announcement of standing by, the concern is of course mitigated. In Maastricht the ATCO makes at that moment a system input showing the flight is on his frequency, and so from then on it cannot be forgotten. 

Even when the air station is not calling in at all, the transferring sector can see that nobody in Maastricht is making this input of starting communications with that flight, and will point that out to the receiving MUAC sector.

MUAC is not using the Stand-By method for transfer of communications to external units.

3. What is the difference to the normal transfer of communications, when Pilots are just required to report Standing-By? 

The biggest difference is that apart from the possible “standing-by” announcement, to which no reply is to be expected, the initiative for communications  comes from the ground. This allows the ATCOs to do their own frequency time-management, addressing the stations not always in the order of arrival but rather in order of priority.

4. What exact phraseology is to be used?

Transfer of Communications in ATC Sector 1:

        ATC: “SPEEDBIRD 123, standby for Maastricht (on) 118.950”

        Airborne Station: “Standby for Maastricht 118.950,  SPEEDBIRD 123”

Start of Communications in ATC Sector 2:

               Airborne Station: “Maastricht,  SPEEDBIRD 123 Standing by”

               No reply is to be expected! 

ATC has the responsibility to initiate communications and address the flight.

5.     When are pilots are required to report Standing-By, if not called by ATC?

This is perhaps the most important question. By all means, if the pilot would feel unsure: do call in.
When using the phraseology “Maastricht, [Callsign] Standing by”: by all means, please wait for a silence on the radio-frequency before doing so.