The missing plane carrying Cardiff City forward Emiliano Sala is unlikely to have been fitted with a flight recorder, according to the UK's aviation regulator.
So-called black boxes which record flight data and cockpit audio are mandatory in airliners and business jets, and are a vital tool for crash investigators.
But they are not mandatory for light aircraft such as the US-registered Piper Malibu plane which went missing over the Channel on Monday night.
A spokesman for the Civil Aviation Authority said the plane is "unlikely" to have been fitted with a black box.
The weight of the recorders is one of the reasons why they are not normally used by light aircraft manufacturers.
But it is a legal requirement for European aircraft to carry an emergency transmitter to aid search and rescue operations.
The UK's Air Accidents Investigation Branch (AAIB) said it is investigating the loss of the aircraft and is working closely with authorities in the US, France and Argentina.
An AAIB spokesman said: "We will be gathering all the available evidence to conduct a thorough investigation.
"However, if the aircraft is not found it is likely to limit the scope of the investigation."
An official source advised that media reports naming the pilot are incorrect.
PA
