FLIGHT attendants have recalled the horrifying moment they found a mum-of-two's head and torso hanging out of a plane's broken window.

Banking executive Jennifer Riordan was killed when a window on Southwest flight 1380 shattered next to her, sucking her out at 32,000ft.

The chilling new details have been released for the first time as the National Transportation Safety Board began a hearing on Wednesday to investigate the tragedy.

Officials announced the accident was triggered when an engine fan blade broke off, causing a piece of exploded engine cover to shatter the window next to Riordan.

Flight attendant Rachel Fernheimer was attempting to help panicked passengers secure their oxygen marks when he spotted Riordan with her torso, head and arm out of the aircraft.

The sickening death was further traumatising with the lower half of the 43-year-old's body still restrianed by her seat belt as her blood spattered the exterior of the craft.

Following the explosion on the jet carrying 144 passengers and five crew members, smoke filled the cabin as engine shrapnel pierced the window.

Flight attendants Fernheimer and Seanique Mallory desperately tried to pull Riordan back in as the force of the pressure sucked her out.

The two grabbed Riordan's legs as two male passengers tried in vain to secure her body, with one putting his arm out the window to wrap it around her shoulders.

"We got (unintelligible words) a window open and somebody - is out the window". Mallory said on the intercom at the time.

"Yeah everyone still in their seats, we have people have been helpin’ her get in. I don’t know what her condition is, but the window is completely out", she added, according to the transcript.

The NTSB hearing in Washington primarily focused on the design and inspection of the fan blades, which was made by CFM International.

Following the fateful incident, CFM recommended more frequent blade inspections with more advanced technology including ultrasound or electrical current tests.

The blade that broke had reportedly made around 32,000 flights and was last inspected in 2012, according to Mark Hadebank, an engineering official at CFM.

A spokeswoman for CFM said that the company has "responded aggressively" to complete blade inspections after the fatal flight.

Riordan, who was on her way home to Albuquerque, New Mexico, had been described as "the bedrock" of her family by heartbroken husband Michael.

A family statement read: "Jennifer’s vibrancy, passion and love infused our community and reached across our country.

"Her impact on everything and everyone she touched can never be fully measured. She and Mike wrote a love story unlike any other. Her beauty and love is evident through her children."

It added: "In her memory – please remember to always be kind, loving, caring, and sharing."

Pilot Tammie Jo Shults was hailed a hero for safely landing the plane after the mid-air blast tore a gaping hole in the aircraft's side.

The stunned pilot quickly and calmly brought the plane into land at Philadelphia International at 11am at a descent of 3,000ft per minute.

During an extraordinary exchange with air traffic control, the pilot revealed she had "injured passengers" who would require medical help on landing.

In response, air traffic control asked: "Injured passengers OK… and is your plane physically on fire?"

The pilot answered: "Not fire, not fire but part of it's missing. They said there’s a hole and uh… someone went out.”

The Boeing 737 had just departed New York's LaGuardia Airport en-route to Dallas when the left engine exploded and ruptured metal flew towards a window.

Shults immediately diverted towards Philadelphia to make an emergency landing and photos showed what appeared to be jet fuel, oozing from the passenger plane onto the tarmac.

Gary Kelly, CEO and chairman of Southwest revealed he was not aware of any issues with the jet and engine involved in the accident and the plane was last inspected on April 15.

The airport released the following statement: "Southwest Airlines flight 1380, which departed LaGuardia for Dallas Love Field (DAL), diverted to PHL because of an operational event.

"The plane landed safely. No slides were deployed. At this time, passengers are coming down a mobile stairway and are being bussed to the terminal. PHL Flights continue to arrive and depart but passengers should expect delays."

Southwest has about 700 planes, all of them 737s, including more than 500 737-700s like the one involved in the fatal flight.