Not exactly snakes on a plane but United Airlines has endured a turbulent week with a series of passenger related incidents and public relations disasters.

The most notable involved Vietnamese-American doctor David Dao, who was dragged off a flight to make way for the airline's staff. He suffered multiple injuries including a broken nose and also lost two teeth.

From scorpions found on board to handlers caught throwing baggage, here is a look at five high-profile incidents involving the embattled airline.

1. BUG ON THE PLANE

Despite its experience ejecting paying customers, one free rider managed to sneak onto a United flight from Houston, Texas, to Calgary, Canada, on April 9.

The non-paying customer - a scorpion - presented itself to horrified flight attendants and passengers by falling from the overhead compartment onto the head of business class flyer Richard Bell.

In removing the bug, Mr Bell was stung, though no complications arose.

This incident appeared to be better managed than previous cases, as United reached out to Mr Bell, who does not plan to sue, to apologise and offer compensation.

2. TEENS HIT BY LEGGINGS BAN

Two teenage girls decked in leggings allegedly fell foul of the airline's dress code for pass riders - the airline's employees or their dependants who travel at discounted prices - and were denied entry to board a United flight on March 26.

Though the rule applied only to pass riders, the issue morphed into one where United was accused of imposing sexist rules, resulting in a social media firestorm where the airline was criticised for "policing women's clothing".

The company asserted that pass riders were included as its representatives.

The New York Times reported that the girls changed their outfits and waited for the next flight.

3. EMERGENCY LANDING BECAUSE OF AUTISTIC CHILD

In another example of bad decisions, the captain of a United flight allegedly told police he was "uncomfortable" flying with a child diagnosed with autism, according to ABC News.

The incident in May 2015 arose after Ms Donna Beegle repeatedly asked to purchase hot food for her autistic daughter, who had not eaten prior to boarding.

When the flight attendant finally acceded and brought some warm food, what ensued was an announcement that the plane was making an emergency landing due to a "behavioural issue" with a passenger.

Police then boarded and asked the family to disembark.

Public furore erupted, with many calling for a boycott of the airline on Twitter.

4. WAR VET BUMPED OFF FLIGHT TO REMEMBRANCE CEREMONY

In 2013, United suffered a social media fallout after it was revealed the airline had bumped 90-year-old Ewalt Shatz off a flight to Honolulu, Hawaii, where the World War II veteran was due to attend a remembrance ceremony at Pearl Harbour.

Mr Shatz was among 41 passengers chosen to be bumped based on factors like fare class and itinerary.

According to CNN, a United spokesman cited "severe weather in the path" that required "the flight to carry additional fuel and reduce the number of passengers on board by 41".

Despite the justification, United had to grapple with a social media backlash, with some users vowing never to patronise United's services again.

5. UNITED BREAKS GUITARS

In 2008, Canadian singer Dave Carroll and his band, Sons Of Maxwell, boarded a United flight from Halifax, Canada, to Omaha, Nebraska, in the United States.

On a stopover at Chicago's O'Hare airport, the band spotted baggage handlers throwing around their musical instruments, including Carroll's C$3,500 Taylor guitar.

This set off a nine-month correspondence between Carroll, who said the base of his guitar was smashed, and United's customer service agents which ended with one agent denying his claim.

After the dismissal by United, Carroll wrote three songs detailing his fruitless attempts at getting compensation from the airline.

The first, United Breaks Guitars Song One, became an instant YouTube hit and forced the airline to accede.

It also requested permission to use Carroll's music video for its customer service training.

Sources: DaveCarrollMusic (http://www.davecarrollmusic.com/songwriting/united-breaks-guitars/), The Guardian, Hawaii News Now, CNN, The New York Times, ABC News, BBC