Flight Crew Air Transport Pilot (ATP)
Communication Breakdown; Human-Machine Interface
ATC Issue All Types; Conflict Airborne Conflict; Deviation - Altitude Crossing Restriction Not Met; Deviation / Discrepancy - Procedural Clearance
General None Reported / Taken
Aircraft; Procedure; Human Factors
Descending on the LZARD SIX Arrival into Tampa we were told to increase speed to 300 knots or better. There was a B737 behind us. After Crossing JAYJA at FL270 approach asked us to descend to FL180; then 16;000 feet; then 15;000 feet. We complied. Before Leveling at 15;000 feet we were asked to cross OLENE at 13;000 feet and 250 knots. OLENE is depicted as an 'Expect' at 13;000 feet and 250 knots landing south. We acknowledged the request and took immediate action but soon realized that this was outside of safe operating limits. After programming a vertical direct to OLENE at 13;000 feet we got the scratch pad message OVER MAX/VERT meaning the descent angle we had asked for was more than 6 degrees. We did our best to comply with the restriction in a safe manner but were unable to notify approach before reaching the fix. The B737 behind us; given the same instruction; also unable to comply; was telling approach the same thing that we wanted to tell them; 'unable.' After crossing the fix we explained that we had done our best and approach acknowledged that we had been 'close enough.' Clearly the Approach Controller made a mistake. Slowing the B737 down would have been safer than asking us to speed up.
We were told to resume normal speed so I was slowing from the assigned speed of 300 knots to normal of 270.
Pressed by ATC to accelerate due to traffic behind and to descend via step clearances the flight crew of an EMB-175 was unable to make ATC's assigned crossing restriction of 13;000 and 250 KTS at OLENE on the LZARD STAR to TPA.