On Thursday 27 February, Pakistan International Airlines Flight PK-786 lost radio contact with air traffic control (ATC) whilst flying over Central/Eastern Europe. The aircraft arrived in Islamabad on time and without any further incident.

A Pakistan International Airlines Boeing 777-200 operating Flight PK-786 from London Heathrow to Islamabad on Thursday lost radio contact for a space of about 50 minutes.

What happened?

According to reports by The Aviation Herald, ATC first lost contact with Flight PK-786 whilst in German airspace. After passing into Czech airspace, Czech ATC was also unable to get a response from the crew of the Pakistan International Airlines Boeing 777 after multiple attempts to make radio contact. Czech fighter jets were scrambled to escort Flight PK-786 to the border.

The aircraft continued on its scheduled course at FL370, and subsequently passed into Hungarian airspace. The Hungarian Air Force had already deployed its Gripen fighter jets to intercept the aircraft, as the Czech Air Force had given warning ahead of its arrival.

The PIA Boeing 777 remained uncontactable on radio as it passed over Hungary, and only re-established communication as it crossed into Romania. Communication was finally made with Bucharest Area Control at 20:18 UTC. In total, the aircraft did not communicate with ATC for around 50 minutes as it passed over Czechia, Slovakia and Hungary.

PIA Boeing 777
Flight PK-786 was escorted by two different sets of fighter jets. Photo: km30192002 via Flickr

ATCs troubleshooting during the incident

As reported by The Aviation Herald, the crew of the Flight PK-786 did not respond to multiple ATC attempts to restore radio communication. Czech ATC instructed the crew to press ‘ident’ on their transponder. Presumably, this was an attempt to gauge whether the flight was suffering from a one- or two-way radio failure. Czech ATC also tried to reach Flight PK-786 on guard frequency but both attempts fell on deaf ears and the aircraft proceeded to fly towards Slovakia.

Before the flight left the Czech ATC zone, ATC informed the crew of the next frequencies. It looks like this information was also not received. Going off the fact that radio communication was only restored as the aircraft passed into Romanian Area Control, it looks most likely that the crew of PIA Flight PK-786 were oblivious to the multiple attempts to make radio contact. This is most likely due to a mixture of inadequate communication skills and training, which meant that radio commands were not understood, and also being tuned into an incorrect radio frequency for ATC over Czechia, Slovakia and Hungary.

PIA Boeing 777
The cause of the incident remains unclear. Photo: Curimedia via Wikimedia Commons

Why did Flight PK-786 go radio silent?

For the crew of a large commercial flight to not notice multiple requests for contact, there must have been a significant breach of protocol by the crew. This is especially true given that the aircraft was passing between multiple ATC areas and also being escorted by two different sets of fighter jets,

At this time it remains unknown exactly what was happening in the cockpit and why there was no response. Simple Flying has reached out to Pakistan International Airlines with a request for comment on the incident. We also inquired about the reason for the lack of radio communication whilst flying over Central/Eastern Europe. The airline has not yet been able to respond to the request, but we will update this article once we receive more information.