Two small fires which broke out on a Monarch plane are believed to have been started deliberately by a passenger.
West Midlands Police have launched an inquiry into the incidents on a Monarch service from Birmingham Airport to Sharm el-Sheikh in Egypt.
The force said no-one was hurt as both blazes were contained and extinguished by staff on board the flight on Thursday August 27.
A police spokesman said: "Officers from the Airport Policing Unit continue to investigate the circumstances around the incidents.
"At present no arrests have been made but our inquiries are still ongoing."
In a statement, Monarch Airlines said local police were in attendance when flight ZB472, an Airbus A321 carrying 201 passengers and seven crew, touched down in Egypt.
"UK authorities have been notified and are dealing with the matter. As the alleged incident is the subject of a police investigation, we are not in a position to comment further," the airline said.
An airline pilot has been suspended after being arrested at Birmingham Airport on suspicion of being over the legal alcohol limit.
The 51-year-old man, who works for airline Thomson Airways, was detained by West Midlands Police.
The incident took place on Sunday February 10, although details have only just emerged.
The pilot has since been told he will face no further police action, Thomson is carrying out its own investigation into the incident.
A spokeswoman for the airline said: "Thomson Airways is aware that allegations of an aviation offence brought against one of our pilots have been dropped.
"However, we are continuing to conduct an internal investigation into the situation, and the pilot in question has been suspended.
"We are not able to comment further until our investigations are complete."
The pilot, who has not been named, was initially released on bail pending further inquiries after being arrested inside the airport on suspicion of being unfit to perform aviation duties due to drink.
A report has found that border officials at Birmingham Airport could have been carrying out illegal bag searches, without the passengers' knowledge.
It said: "Despite the fact that the current Border Force enforcement handbook guidance prohibited this activity, staff confirmed they were carrying out covert baggage searches."
A Border Force spokesman said:
Illegal luggage searches could have been conducted by border officials at one of Britain's busiest airports, without the passengers' knowledge.
Over 1,000 pieces of luggage were seized at Birmingham Airport in the year to September.
However, Chief Inspector of Borders and Immigration John Vine said there was no record of the instances in which these searches did not result in a successful seizure.
Because of this, there is no way of knowing the total number of searches conducted in the period, and whether border staff were breaching passengers' rights.