Failures in commercial aviation are incredibly rare thanks to a culture completely dedicated to flight safety. When things do go wrong, pilots and air traffic controllers can rely on standardized procedures that have developed from years of learning and experience. A great example of such a procedure is that which is undertaken in the event of a radio failure, or a ‘NORDO’ situation. Let’s take a look at what actions are taken when an aircraft’s radio goes on the fritz.
What immediate actions do pilots take in the event of a radio failure?
Pilots have several procedures and alternative communication methods they can use to ensure safe operation and maintain communication with air traffic control and other aircraft if their radio fails.
Troubleshooting – Pilots may attempt basic troubleshooting procedures to determine if the radio failure is due to a minor issue that can be resolved. This could involve checking the radio settings, connections, and power supply. Taking the time to do this may reveal anything from a mis-entered frequency to an electrical issue.
Backup radio – most aircraft are equipped with multiple communication radios, referred to as COM1 and COM2, so pilots can switch to the second radio if the primary one fails.
Squawking 7600 – if all radio communication is lost, pilots can set their aircraft’s transponder to the emergency code 7600. This code alerts ATC that the aircraft is experiencing radio communication failure, and ATC will know to expect certain actions from the aircraft.
What happens next?
The next actions depend to some extent on the type of flight and conditions under which the aircraft is operating.
Radio failures in Visual Meteorological Conditions
Aircraft operating in Visual Meteorological Conditions (VMC) under Visual Flight Rules (VFR) must first squawk 7600. If the aircraft is operating in an airfield’s circuit pattern (also known as a traffic pattern), the pilot can follow visual signals from the ground, most likely using red and green lights. If the aircraft is outside the circuit, it must land at the nearest suitable airfield, and remain in VMC conditions.
Radio failures in Instrument Meteorological Conditions
Aircraft operating in Instrument Meteorological Conditions (IMC) under Instrument Flight Rules (IFR) will also squawk 7600 as soon as possible. Following this, IFR aircraft have more specific procedures to follow. Here’s a simplified summary…
- Maintain the last assigned speed, and the most recently assigned level or minimum safe altitude (whichever is higher) for 7 minutes. This time allows air traffic to coordinate their actions.
- Fly the flight levels and speeds as specified in the flight plan. If the aircraft was being vectored by ATC at the time of the failure, the flight will proceed in the most direct manner to the planned routing.
- Follow the flight plan to the designated navigation aid at the destination airport.
- Begin the approach from that navigation aid at the last acknowledged approach time or the estimated time of arrival based on the current flight plan.
- Fly the normal instrument approach procedure and land within 30 minutes after the ETA (a VFR aircraft should also try to land within that 30-minute period).
These are the basic steps aircraft are mandated to follow. The arrival airport will have its own specific radio failure procedures. These can be found within the approach charts and supplementary documents. This could mean specific actions are required during the approach and after landing, or even ban aircraft with no radio from landing altogether.
Other ways to get in touch
- In some instances, radio transmissions can be relayed to air traffic control via another aircraft nearby. This can be particularly helpful in remote areas or during non-radar operations.
- Pilots of large commercial aircraft often have secondary communication methods, in addition to radio, that could be used as backups. These include data link communication systems, such as ACARS (Aircraft Communications Addressing and Reporting System), which allows pilots to send and receive messages from dispatchers. This could be used in a lost comms situation to pass messages along to ATC.
- Another evolving system is CPDLC (Controller-Pilot Data Link Communications). This system essentially allows air traffic to control to communicate with the aircraft via an automated or manual text message. This technology is quite literally designed to replace radio, and means that aircraft flying oceanic transits can receive information without resorting to poor quality UHF (Ultra High Frequency) transmissions.
It is important to emphasize that complete radio failures are relatively rare. Aircraft systems undergo stringent maintenance and checks to minimize the chances of failure, and benefit from carrying several radios on board. Pilots are trained to follow procedures and ensure a safe conclusion of the flight.
How to identify aircraft with failed radios on Flightradar24
You can easily identify aircraft squawking 7600 with alerts on flightradar24, just tap the bell icon in your app and toggle ‘Squawk 7600’ on.
Cover image: Randall Johnson, JetPhotos.
