Archive for pilot comparison

Pilot Report: Boeing 737 vs. McDonnell-Douglas MD-80

Posted in airliner, flight crew, jet, pilot with tags , , , , , on December 17, 2011 by Chris Manno

Now that I have nearly a thousand hours in the left seat of the Boeing 737-800, and having as well over 15,000 in the MD-80, I feel qualified to make some judgments about how the two stack up against each other.

For me, there’s one hands-down winner. I’ll get to that.

But first, looking at it from a hands-on pilot perspective, let me say what I think are the crucial factors in both jets, then compare them. And I’ll do it in order of importance from my line-swine pilot view:

1. Power: never mind the technology difference between the General Electric JT8D turbo fans on the Maddog and the CFM-56 high-bypass fans on the 737. It’s the thrust difference I want in my right hand when I’m trying to lift 170,000 pounds off a runway. And technology aside (I’ll get to that), the three full power options (22,000, 24,000, and 26,000 pounds of thrust) plus the bonus kick up to 27,000 pounds per engine on the 737 for special use beats the snot out of the 19,000 flat rated and standard de-rated engines on the MD-80. Yes, the -80 weighs less than the 737 (max of 150,000 vs. 174,000 pounds), and no, I don’t have each plane makers’ specs, but the thrust-to-weight performance from the left seat feels substantially more secure and significant from the 737.

You notice that right away when you do a static takeoff with the 737 at all weights: you’ve got buttloads of giddyup (I think engineers call it “acceleration,” but then they don’t actually feel it on paper versus in the cockpit blasting forward–that’s “a buttload of giddyup”) shortening  those critical moments of vulnerability between brake release and V1.

I have no idea what engineers think of when they look at thrust and take-off advantages, but any pilot with experience knows that those seconds before reaching flying speed are the most vulnerable, particularly close to max abort speed, because I’d rather take any problems into the air than have to wrestle them to a stop on a runway. The MD-80 has good smash at mid to light weights, but in crucial situations (Mexico City, for example, or on a short runway on a hot day) the 737’s CFM56’s rule. I need the shortest possible period of on-runway vulnerability; I know engine hot-section limits and longterm life are important too, but the CFM56 achieves better on-wing engine endurance in operation than the JT8Ds, year over year.

Ditto for a go-around or windshear options: the MD-80 is famous for it’s slow acceleration–I’ve been there MANY times–and when you’re escaping from windshear or terrain, I can promise you the pucker factor of the “one, Mississippi, two Mississippi” on up to six to eight seconds will have your butt chewing up the seat cushion like horse’s lips. Not sure if that’s due to the neanderthal 1970’s vintage hydro-mechanical fuel control (reliably simple–but painstakingly slow to spool) or the natural limitation of so many rotor stages. But the 737’s solid state EICAS computers reading seventy-teen parameters and trimming the CFMs accordingly seem to give the performance a clear edge. And a fistful of 737-800 throttles beats the same deal on the Maddog, period. Advantage, Boeing.

2. Wing: let me go back in time. I also flew the F-100 for a couple years as captain. That was a great jet, with a simple wing: no leading edge devices. Coming from jets with slats the feel was clearly different on take-off, where there was a distinct (if you’re a seat-of-the-pants guy, and that’s all I’ve ever been) translational period between rotate and lift-off due to the hard wing. Ditto in the flare and in some reversals in flight like on a go-around. Not a bad thing, just something you had to anticipate, but not a warm-fuzzy in the seat of your aerodynamic pants.

Stretched jet, stretched wing.

That’s a good analogy between the Boeing versus the Douglas wing: you feel the generous lift margin in the 737. That’s because when Boeing stretched the jet to the -800 length, they expanded the wing as well. That wing was already loaded much lighter than the DC-9 wing which Douglas didn’t enlarge when they added to two fuselage plugs plus about 15,000 pounds to the MD-80. Longer and with better cambered  (look at the DC-10, and no dihedral) airfoil is the Boeing design and I’m grateful for their foresight and superior engineering–especially at the top end of the performance envelope: you need anti-ice? No problem–turn it on. The Maddog? Better be 2,000 feet below optimum, or prepare for stall recovery–and anyone on the -80 fleet knows I’m not exagerating. Wing performance? No contest: Boeing.

3. Handling: again let me go back in time. Flew the T-37 like every new Air Force pilot up until recently–then moved on to the T-38. Using standard Tweet inputs on The Rocket would bang your helmet off the canopy because of the boosted flight controls, giving you 720 degrees of roll in a second at full deflection.

That’s the 737 compared to the MD-80: no aileron boost on the -80, and little help from the powered rudder–because of the long fuselage length and relatively short moment arm between the vertical fin and the MAC (Mean Aerodynamic Chord), the rudder seems to only impart a twisting moment that’s pretty useless. So it’s a wrestling match for roll control, in and out of turns with the -80.

I still tend to over control the 737 in acute roll situations (e.g., the 30 degree offset final at 300′ AGL required in and out of DCA) due to previous brain damage caused by years of arm wrestling the MD-80 around tight corners. But with the 737, the seat-of-the-pants security of that generous wing is apparent at all speed and altitudes and the hydraulic aileron boost gives you the muscle to command a smooth and prompt response. Handling? It’s all 737 for me, including on the ground: new MD-80 captains will need Ibuprofen to counter the wrist strain of the nosewheel steering, two-handed in tight spots. I don’t miss that at all.

4. Cockpit layout: okay, give the -80 its due–that was one comfortable nest once you got settled. But that’s as far as it goes for me. Yes, I know the 737 kitbag position is inaccessible. But American Airlines is the first airline certified by the FAA for iPad use from the ground to altitude. Kitbag, what’s a kitbag?

MD-80 left seat–HSI? Where is it?

Trade-off? The MD-80 HSI is obscured by the control yoke. Are you kidding me? Like you might need lateral situational awareness for trivia like, navigating? Flying an approach? I spent 20+ years working around that human factors engineering failure–I’m grateful for the Boeing engineers who gave me seven 9″ CRT flat plate displays with every parameter I could want displayed digitally and God bless them all–a Heads Up Display! Lord have mercy, even a simpleton has a crosscheck in that jet thanks to the God of HUD.

The 737 doesn’t have the elbow room you might like and everyone who I fly with who has come off the big Boeings (757, 767, 777) gripes about that. Fine. I’m all about performance and the flight displays, computers, communications and advanced Flight Management Systems in the 737 avionics suite beat the pants off of the 75 and 76–and the HUD tops the 777 as well. Nuff said: gimme the Guppy cockpit over the Maddog. Boeing put everything I need at my fingertips, and it’s all state-of-the-art, whereas Douglas engineers threw everything they could everywhere in the cockpit and slammed the door.

My 737 home.

So there you have it: power, wing, handling and even by a narrow margin, the cockpit too. I’m a Boeing guy, back from wayward days flying Douglas metal from the DC-10 to the MD-80. In my experience as a pilot, in my hours in both Boeing and Douglas jets, I’m grateful to be flying the best jets in the sky. Now you know which are which.

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