On 17th April 2018, Southwest 1380, a Boeing 737-700, was cruising about FL320 when it suffered a catastrophic failure to engine 1. It then took 5 minutes to descend to 10,000 feet, and I noted from the ATC recordings that the pilot said it would require a long approach to land at PHL.
Is this because the airplane could not bleed off airspeed fast enough for a short/straight-in approach? Is this the fastest that a large commercial airplane can descend and slow for an emergency landing?
I assume that, to achieve maximum descent and deceleration the remaining engine would be pulled to idle, and that landing gear would be extended at maximum safe speed, which IIRC is 250 knots?
Would it be reasonable to fly cross-controlled with an aircraft in this condition? With no engine thrust requiring rudder input, is that safe at all speeds? How much can it increase drag?
What are the speed limits for extending flaps, and how much do those affect drag?
(I can appreciate that in the case of Southwest 1380 the pilot in command, not knowing the extent of damage, may have been hesitant to do anything that would strain the airframe or controls. So I'm curious as to how long an "unstressed" descent would take, and then how much faster one could descend by using the most aggressive techniques that a pilot would reasonably use in an uncompromised passenger flight in the same model.)