Open Air Burning of Bodies at Auschwitz

Hmmm...

I never heard of this until I saw this recent NYTimes piece:

EUROPE A Holocaust Survivor Tells of Auschwitz at 18 and, Again, at 90

MARCH 13, 2015 The Saturday Profile 

By ALISON SMALE BUDAPEST — 

HIGH above the hubbub of Budapest’s main tourist street, Eva Fahidi flits, birdlike, around her warm apartment, lined with books and plants. The setting is cozy, and the hostess and narrator, at 90, a lingeringly beautiful charmer. 

So the contrast with the Holocaust horror she is describing is all the more complete. When she was 18, she was, as she put it, “ripped off the school bench to be deported to Auschwitz­Birkenau,” one of an estimated 437,000 Hungarian Jews rounded up outside Budapest and dispatched to death camps in just 57 days in 1944. Auschwitz­Birkenau, she recalled, “was not ready. It was too fast. The gas chambers were big enough that people could still be suffocated to death. But the crematories could not manage. 

So corpses were being burned on open fires.” “Really, at the very first moment you knew something was wrong. It was the huge stench of burning corpses — only we didn’t know.” 

Ms. Fahidi lost 49 relatives in the Holocaust, including her mother and sister Gilike, then 11. Her last glimpse of them was on the ramp at Birkenau, where arriving Jews were sorted into those sent instantly to the gas chambers...

This holocaust history site says yes, this happened, then talks about aerial photographs and has a dead link of an aerial photo supposedly showing the burning pits.

So, one thing for sure is open air burning is not going to be very efficient... and if thousands of bodies were burned in outside pits, there should be some traces left of this, no?

This picture is supposed to show this outside burning at Auschwitz, but while there seem to be naked bodies and smoke, not much else is clear.

Carlo Mattogno has written a book supposedly refuting this, but I have not read it it.