A US Navy P-8A Poseidon is one of the aircraft searching for missing Malaysia Airlines flight MH370. It searched more than 36,000-square kilometres yesterday and was diverted to try and verify objects spotted by the Australian military. ABC reporter Emily Piesse was on board.
It is the fifth time the P-8A Poseidon has been sent to the search area, about 2,500 kilometres south-west of Perth.
The pilots quickly reach an altitude of 32,500 feet and it is a fairly smooth ride for the next three hours. The rest of the crew spends the time preparing for the job ahead.
In the middle of the plane, where passengers would usually sit, is a row of five work stations. Each terminal has two large computer screens set at angles, like an open laptop, and a radio.
The screens show one of three pictures: a video feed from a camera mounted underneath the plane, at the rear of the cockpit; a computer graphic of the plane's position relative to other parts of the search area; and the plane's radar.
Four of the officers are trained to interpret information from the radar. Another two are tactical coordinators, tracking the Poseidon's path through the search zone.
There are also two observational windows on opposite sides of the aircraft. Despite all the advanced technology, the crew will still depend on a manual check if debris is found.
The 'ladder' search zone
The search area is a rectangular grid, divided into six lanes similar to a swimming pool. The US is responsible for the middle section, which is about 320 kilometres by 32 kilometres.
Aircraft from other countries, including Australia, have been tasked with searching the outside lanes.
The Poseidon flies four lengths of the grid, taking about 45 minutes to complete each one. It is called a "ladder search" because the plane banks at each end and returns in the direction it came from, one step higher than before. Each track is five miles apart.
The plane descends once it reaches the search area, heading below 1,000 feet.
Visibility is good at first; the sky is light grey but there is some blue showing through and the water is vivid. It is easy to see whether there is anything below.
Midway through the first pass the plane makes several tight turns to investigate an object on the radar, but it turns out to be seaweed. The crew says there have been plenty of false alarms on other days, including pods of dolphins.
Unfortunately, the good weather conditions do not last. There is thick fog over a third of the search area and low-lying cloud elsewhere.
Atmosphere tense as crew hunts
The plane has almost finished its final search leg when it is diverted to a nearby area outside the US zone.
The Australian ship HMAS Success has spotted objects in the water, but lost them due to poor weather.
One of the officers says an Australian P-3 aircraft also reported "colours and shapes" in the water.
At this point, the Poseidon has 30 minutes worth of fuel for searching before it will need to head back; by the time it reaches the new area, there is just 20 minutes of fuel left.
There are three potential debris sites showing on the plane's radar. Officers are silent and the atmosphere is tense as the plane makes four passes over the area.
Visibility is poor and the pilot takes the aircraft to just 200 feet in an effort to clear the cloud. No-one can see the objects.
One of the pilots, Lieutenant Clayton Hunt, says he is confident there is something on the radar but "it could be anything".
Poor weather hampers search
As the plane heads back to Perth Airport, the crew says visibility in the final, crucial stages of the search was on par with the worst conditions they have seen during the search for MH370.
Despite failing to find the possible debris, Lieutenant Commander Mike Trumbull says "as long as it remains afloat, the ship will be able to locate it".
At three hours and forty-five minutes, it is the longest search conducted by the US during this mission.
And with a flight altitude of 200 feet at times, it is also the lowest the Poseidon has flown.