Breaking Through

STS-53 Landing

Watching the HUD video during Discovery’s landing yesterday made me think of Dave Walker and STS-53.  The video feed (which is not great quality) showed low clouds obscuring the visual landing aids until fairly low in the final approach.  Probably not a flight rule violation, but then neither was the day I sent Dave to Edwards and there was this one cloud . . .

 

Dave Walker was a decorated Naval Aviator, and he is no longer with us.  I miss him.  But the most important thing to know is that Dave Walker was a true individual.  One might say he was colorful.  Or a character.  Dave was the commander of STS-53 and I was the Ascent/Entry Flight Director.  That means I had a dog name.  Oh yes.  That was Dave’s idea.

Dave drove an old – I mean really old – station wagon to work and parked it in the lot by building 4.  It was so old that he repainted it white.  It was not a great paint job.  Then Dave found a T-38 wingtip that had been damaged out at Ellington field and was going to be scrapped.  He took it home and affixed it to the top of the station wagon.  He named his vehicle “the dog mobile”.  Yep.  And everybody in his crew and the trainers and flight controllers all got dog names.  Dave was “top dog”.  Jim Voss, one of the mission specialists who was an officer in the US Army was “dog face”.  You get the picture.  Somewhere in the pilot jargon, a “sled” is a really fast airplane.  Since my job involved them flying really fast, I became “sled dog”.  Oh my.  Everybody got a dog name.  If you were lucky you got to ride in the dog mobile.

Colorful.

But he was no nonsense about flying, and we had a big flying challenge on STS-53.  We were going to demonstrate the shuttle autoland system.

The space shuttle had been designed with the capability to autoland without pilot intervention but there were certain . . . quirks . . . in the system.  It was not deemed safe in the early days.  After 40 or 50 flights, it appeared that those . . . quirks . . . had been gradually fixed.  Of course, landing had to be on a runway equipped with special ground equipment.  The MSBLS (Microwave Scanning Beam Landing System) was built especially for the space shuttle.  If you ever look closely at a shuttle landing you might see a couple of small metal buildings painted red and white just to the side of the runway threshold.  These buildings contained the complex equipment to send out a sophisticated radio beacon which would allow the shuttle to navigate safely to the ground.  If it all worked right.  Which might not be the case.  All the shuttle flights before this relied on the eyes and judgment of the commander to fly the final approach and landing.  This required certain weather restrictions, like the limitation that the bottom clouds must be no lower than 8,000 feet above the ground.

A lot of those launch scrubs or landing day wave offs are due to low clouds, or the possibility of low clouds, or the worry about low clouds in the landing area of the shuttle.  Just so the commander can see the PAPI (precision approach pilot indicator) lights in time to adjust the shuttle trajectory if the navigation was in error.  Which MSBLS could do to you.  Until they fixed those, you know, quirks.

Ostensibly, we needed auto land because the shuttle flights were getting longer and longer and there was a real concern (raised by the doctors) that the commander might become disoriented during landing after a long period in zero gravity.  It was a safety thing, we were told.  All of us in the Flight Director’s office wanted auto land to get away from those pesky low cloud rules that kept us waving off.

Dave took the challenge seriously.  We flew the simulators and the Shuttle Training Aircraft a huge number of times with various navigation errors and offsets, problems with the MSBLS or other navigation sensors, visibility restrictions and low clouds.  We developed a set of flight rules to determine when we would attempt an auto land and when we would not, when the commander would take over manually, and when he would let it land automatically.  The real danger lay in a late manual takeover – by definition in a bad situation – where the commander couldn’t get it back to the runway in time.  So we practiced and practiced and studied and analyzed.

About three weeks before the flight General Jedidiah Pearson weighed in.  General Jed was one of those revolving door retired flag officers that seemed to wind up at NASA periodically.  He was probably a great general.  And since his job was at NASA headquarters his main responsibilities were inside the beltway and I am sure he did a fine job.  He was always nice to me.  But I got the real impression that he never really understood what we were up against, never really understood what human spaceflight involved.  Its not like being a fighter pilot commander in the military.  So as much as I liked him personally, his decision at launch – 3 weeks to call off the autoland test rankled me  He said we would never fly a pilot in space long enough to get them disoriented and therefore we did not need the autoland demonstration.

I was really mad, but Dave counseled patience.  Top dog was right.  We flew the flight – it was very successful – until the very end when Dave and I each took a turn and almost crashed Discovery.  For real.

So I guess I can’t quit the story now.

Landing at KSC was no go.  It was perfectly beautiful at the Shuttle Landing Facility, but there was a weather front approaching which had a sharp edge of very low clouds.  We had been watching the weather for hours and this implacable layer of clouds was marching toward the SLF with military precision.  Given the winds aloft, the SLF would be clear and unlimited visibility at deorbit time, and totally overcast at landing time an hour later.  KSC was no go.

At Edwards, Dick Richards was flying weather reconnaissance for us.  Dick was a very experienced shuttle commander and he knew what was OK and what was not.  There was just one cloud in the sky.  You guessed it.  Right over the PAPI lights with a bottom lower than 3,000 feet.  One cloud did not violate the flight rules – we were allowed to have scattered clouds.  And there was a good wind aloft.  No way that cloud was going to stay there for the hour between deorbit burn and landing.  But Dick made it crystal clear – he was NO GO.  Do not attempt to land here, he told us over the radio.

But I was the Flight Director and the decision was up to me.  The weather forecaster and I conferred.  One cloud.  Couldn’t possibly stay there for an hour.  I gave the crew a GO for the deorbit burn.  I thought Dick was going to climb through the radio headset and stop me.

A funny thing happened back in Florida.  That line of clouds associated with the cold front pulled up short, about 40 or so miles north of the SLF.  My weather forecasters couldn’t explain it.  The SLF was perfectly clear at the scheduled landing time.  But the shuttle was on the way to Florida.

And the cloud over the PAPI lights at Edwards?  You guessed it.  It didn’t move; it just grew bigger.  In the debriefing, Dave told me that somebody “had some‘splainin’ to do” over that cloud.  He was right.  I was that somebody.  My boss, the head of MOD, took me aside and said, “3,000 feet is too low”.  He was right.  The weather guys couldn’t explain that cloud either.

But Dave got distracted at a critical moment in the entry and was about 10 seconds late turning the shuttle on its final heading.  Almost over-g’d the vehicle. But he got it back on track and made it through the cloud and landed safely.  Like nothing had happened.  Whew.  Any landing you can walk away from is a good one.

We wrote down several lessons after STS-53.  About clouds and weather; aboutthe use of autoland; about turning on the HAC.

But I still wish Dave had been given the chance to demonstrate the autolanding system.  I think it will work fine.  There were just some concerns about . . . quirks . . . in the system.