Reply #10: Big difference if you are referring to number of engines .. [View All]

[DemoTex]

Thrust-to-weight ratios are always better in two-engine jets than three or four, because of engine failure criteria of FAR 25 (? IIRC) certification rules.

But engine failures are very, very rare on modern transport category jets. What is much more common/likely/deadly is an encounter with low-level wind-shear. The higher the T/W ratio the better the chance of flying out of a low-level wind-shear safely. Alternatively stated, I'd rather be in a twin-jet (high thrust-to-weight ratio) Boeing 737-300 attempting a low-level wind-shear escape maneuver than a Boeing 727 (3-motors) or Boeing 747 (4-motors)!