Mustang1977 wrote on Feb 1^st, 2015 at 8:18am:

Markoz wrote on Feb 1st, 2015 at 1:52am: His speed may be MACH 0.7, but the airspeed indicator shows about 190 knots and that is way too slow, even at 12,500 metres. :o Attention, 12.500 metres are near 41.000 feet - 190 KIAS for that alt would be alright.

At 41,000 feet, with a gross weight of 189,764 pounds (payload 19,420 and 27,344 pounds of fuel (~18% fuel)) and flying at 190 knots (MACH speed was about 0.67/0.68), my 707-300 had a very pronounced rocking left & right. It really looked like it was on the verge of stalling. While 190 knots at 41,000 feet may not be a stall at that weight/altitude, it is certainly not very stable. In fact, it all started once the speed dropped to about 250 KIAS, and got worse as I slowed. When I throttled up, it took forever to gain much speed (after 5 minutes I was only doing 230 KIAS with full throttle) all the while rocking left and right.

Edit. Fuel flow was ~1000 PPH