The helicopter pilot who rescued 28 people stranded on rooftops in south-east Queensland's deadly floods will tell an inquiry this week how his crew relied on a phone for navigation after flooded roads forced them to improvise.

Mark Kempton's statement to the Queensland Floods Commission of Inquiry details the expert efforts of his crew to winch people to safety on January 10, when a wall of water rushed through the Lockyer Valley, west of Brisbane.

The flood claimed 17 lives from the region's close-knit hamlets, and three people remain missing, presumed dead.

Mr Kempton, a pilot for Emergency Management Queensland's helicopter rescue service for 11 years, is expected this week to give evidence to the commission, which sits in Toowoomba from tomorrow.

Mr Kempton is one of the people whose actions during the floods will be recognised with a medal in June.

His story is doubly memorable because while he was saving lives in the Lockyer Valley, his own home in Brisbane's south was flooded.

In a statement, he recalls how his chopper arrived over Grantham shortly before 5:00pm on January 10 and his crew were shocked at the sight of the brown water rushing beneath them, taking water tanks, trucks, boats and an aeroplane with it.

They were able to winch 28 people and one stowaway cat to safety in fading light and with dwindling fuel before they were relieved by a second helicopter some time after 6:00pm.

"There were still many people trapped on rooftops and it was extremely difficult to have to fly away and leave them to their fate," Mr Kempton's statement said.

The following day the crew was sent to search for survivors in the Murphys Creek area, but due to the flooded roads below their maps were useless and they were forced to improvise using Google Maps on a crew member's iPhone.

Hours later, as they were trying to return to base to refuel, Mr Kempton got news that his home was flooding.

Their return was hampered by bad weather, and when the crew asked for a military tanker to come to them, they were told it could be four hours before they got approval from Canberra.

Mr Kempton says the rescuers could have done more that night if the helicopter had been upgraded to carry more fuel and had a better winch, as well as a better map system.

As well as frustrations with Defence bureaucracy, he describes arguments with Queensland Health, which wanted the crew to perform hospital transfers while the search was continuing.

Flood survivors will tell the inquiry there was little preparation for the flood despite weeks of rain, no warning of the coming disaster, and a lacklustre response from the local council.

The inquiry before commissioner Justice Catherine Holmes will sit in Toowoomba until Friday.

- AAP