An Army test group was told it was marching "inside the window" of safety on the hottest day of the year before a soldier fatally collapsed, an inquest has heard.
Corporal Joshua Hoole, from Ecclefechan, died during an annual fitness test (AFT) at Brecon in Wales, on the morning of July 19 2016.
An inquest into Cpl Hoole's death has already been told that soldiers were aware it was to be "the hottest day" and the march start time was brought forward four hours, due to the weather.
Of the 41 corporals and lance corporals taking part in the AFT that day, 18 pulled out, collapsed or withdrew - a rate of 42%.
The inquest at Birmingham Coroner's Court has previously heard the average drop-out rate on the same route for the whole of the previous year had been 3%.
Cpl Hoole, 26, collapsed at 8.52am just 400m from the end of the "eight-miler" loaded march.
Earlier on in the route, two other soldiers had suffered suspected heat injuries.
The inquest has heard a key temperature gauge used to determine if it was safe to start AFTs had been "erroneously" located in the shade of the base's gym at Dering Lines, meaning it gave low readings in the morning.
Exercises are not supposed to go ahead if the wet bulb globe thermometer (WBGT) hits 20C, senior coroner Louise Hunt has been told.
On Monday, the inquest heard a call was made - while the march was in progress and 27 minutes before Cpl Hoole collapsed - asking for the temperature reading but one was not available.
The phone call by a member of the march directing staff, Sergeant Daniel Northeast, was made to staff at Sennybridge Army camp, where they also have a WBGT, as he had the number in his phone.
That camp is 10 miles from Dering Lines and in any case, on the day the machine was away for calibration.
A statement by Sergeant Northeast, read to court, said: "I had a discussion with the guy on the phone, and I know they have a wet bulb globe thermometer.
"He didn't give me the temperature but told me we were still inside the window (of safe operating) and it would be sensible to take on water," added the sergeant.
He added: "I told him thanks, but it wasn't really what I wanted to know."
The sergeant had a Garmin watch which was capable of taking a temperature reading, when linked to a thermometer on his rusk sack.
However, just after the half-way stage when march had completed a steep hill, he was unable to get a reading so checked on the internet using his mobile phone.
He said that at no stage did the temperature rise to 20C, as far as he wasconcerned.
"It was 17C when the march started, got to 18C by my phone, using an internet signal and then ended at 19.99C - by my watch," he added.
The court has previously heard that by 10am, an hour after Cpl Hoole collapsed, the WBGT reading at Dering Lines had reached 25.5C.
The inquest continues.