An Air India Boeing 787 Dreamliner recently diverted its Melbourne-Delhi flight to Singapore, but not for the usual reasons: After all, the weather was clear, no fist fights broke out on board, and there wasn't a medical emergency. Instead, the plane had to change course because of another sort of unruly, unwelcome passenger: a rat.

Apologies, optimists, but this isn't the first time a rat has been spotted on-board this specific Dreamliner—it's the third time in a month. Two weeks ago, one was spotted stretching its legs mid-flight from Birmingham to Delhi, and then another interrupted the boarding process on a Delhi-Frankfurt trip. Each time this has occurred, the plane has been grounded and fumigated, but seemingly to no avail. So, is this a particularly resilient Delhi-based rat trying to see the world, or are these multiple rats who seem to favor Air India Dreamliners? "There is no way to know if the same rat was seen on those three occasions," a source told the Times of India. "But if it is so, this is a very sturdy rodent we are talking of as the aircraft was fumigated, laid with rat traps, and locked up for several hours after both sightings."

Rats have also been sighted on other aircrafts in the airline's fleet: Passengers got an unwelcome holiday surprise when in late December 2015, a flight to London had to return to Mumbai after a rat was spotted on board, and last July, a Milan-bound flight had to turn back to Delhi for the same reason.

This time, the rat problem has gone all the way to the top: the Business Standard reports that Air India chairman Ashwani Lohani has personally carried out an inspection of Delhi's Indira Gandhi International Airport, paying particular attention to the hi-lift catering trucks that load food onto the plane, and banning employees from eating around the ramp area.

Anyone who has taken a ride on the New York subway has no doubt had some sort of close encounter with rodents, whether it's viewing one hauling a slice of pizza out of the station or hitching a ride uptown. But on a plane, the solution is not as easy as stomping your feet and hoping the intruder runs back into the dark abyss. In addition to hygiene issues and the passenger anxiety that comes from being trapped in an airplane cabin with a rat for hours at a time, there are resulting safety concerns: Rats have a taste for wiring, and a gnawed cable could lead to serious mechanical failures. Should the rat evade the exterminators once again and take another Air India trip, let's just hope it's satisfying its wanderlust like the rest of us, and not looking to make a meal out of vital electronic equipment.