Wednesday, October 27, 2010

Instrument Flying Part II-It was early one Saturday morning.....

It was early Saturday morning in Burlington VT (BTV). I was there to fly N711EB, a Piper Navajo to Manchester, NH (MHT), a typical freight run. The date was May 30 1989, Memorial day. Weather was basically VFR with a chance for IFR in Manchester. Recent passage of a cold front raised the possibility of some ground fog, especially in the early morning.

Before heading to the flight line to do my preflight check of the plane, I needed to call the Burlington flight service station for a last minute check of the weather and to file my IFR flight plan to Manchester and back. Nothing new with the weather. I requested 9000 feet for altitude going to MHT. Estimated flight time was 30 minutes. Fuel aboard the Pa31 was 4 hours. Plenty to get there and return to BTV if I couldn’t land in Manchester. Did a quick preflight and got up into the cockpit. I loved to fly the Navajos, big and roomy with plenty of power and full de-ice capability.

After engine start and checking the various things on the after start check list, I set up the radios for communication and navigation. First I would listen to ATIS (automated terminal info service) which told weather on the field and gave taxi and runway info. As the ATIS is updated a different letter of the alphabet is assigned to it, e.g. ATIS Info foxtrot. Anyway, I copied the ATIS foxtrot and called ground control or maybe clearance to obtain my IFR routing. “ Burlington clearance N711EB IFR Manchester for clearance”. The reply: N711EB you are cleared to Manchester as filed expect 9000 as final altitude”. After confirming what I had heard I was told to contact ground control. Ground control cleared me to taxi to and hold short of runway 15. After reaching the hold point at runway 15 I did the usual pre take-off check. There is an acronym, CIGAR, standing for controls, instruments, gas, attitude, run-up. This a short cut to a lengthier printed protocol, but is sufficient for the pilot proficient in that airplane. It wouldn’t work for much more complex airline type planes, where checklists are pages long. Anyhow after checking everything: engines, radios, trim, gas and the controls I called the tower for take-off clearance. I was cleared to take-off on runway heading to 3000 feet. I taxied into position and pushed both throttles forward to the stops. Satisfied that all was A_OK I released the brakes and began my take-off roll.

As I rapidly accelerated down the runway, keeping my eye on the ASI (air speed indicator), I started pulling back on the wheel lifting the nose off and beginning my climb out. The runway heading of 150 degrees essentially placed me on the airway (V141), which would take us (the plane and me) all the way to MHT. On route we would fly over LEB (Lebanon, NH) and CON (Concord, NH) with little heading change. Minimum altitudes out of BTV were 6000 once on the airway, to avoid the tops of the Green Mountains.

Once airborne, I was told to contact departure control by the tower operator. “Departure N711EB is out of 1500 for 3000”. “ 711EB clear on course, climb to requested altitude of 9000”. “711EB, roger”. After passing through 6000' I was handed off to Boston Center: "Boston 711EB 6000". They replied" cleared to maintain Niner thousand". In 25 minutes I was passing over LEB vortac (VOR) and then on to Concord VOR (CON). Just a little course correction to the south and we are headed for MHN. Engines are purring nicely, all gages are in the “green”. As we are only about 15 minutes out from our destination, I tune in the MHT ATIS and whoa! The weather is not good. Indefinite ceiling 100’, RVR (runway visual range) 3000’, ground fog. That is below minimums which are:200’ ceiling and visibility ½ mile (200 and a half) for the ILS to runway 17, the active at this time. OK I’ll just continue and hope conditions improve. I can elect to shoot the approach and if I make it because things are better than advertised great, if not I’ll do a missed approach and either try again or enter a hold as directed by ATC. Boston handed me off to Manchester Approach and the fun began.

Before long I was told to descend to 4000‘and intercept the RWY 17 localizer and follow it inbound. Then descend to 3000’ and “cleared for the approach to RWY 17”.
Shortly after I was cleared for the approach by ATC, I was advised that the previous flight had “missed”. After completing the pre landing checklist I decided to continue and give it a try. Down into the murk I we went. Cotton wool all around, absolutely no visual cues. The autopilot was on but I constantly cross checked the attitude indicator, airspeed and altimeter. The navigation indicator for flying the ILS was constantly monitored. It very accurately shows one left or right of course or above or below the glide slope. The latter is most critical when getting down below 500’. At the outer marker, I lowered the landing gear and flaps and began the descent to the field.

Anyway, arriving at the final decision point: altitude 429 feet (200 above the runway) and about ¼ mile short of the runway, still nothing but murk. So after continuing for about 5 seconds, I advanced the throttles and after ascertaining that we had a positive rate of climb, retracted the gear and the flaps. Then after all that done, I advised the tower that I was executing a missed approach. “ Manchester tower 711EB missed approach”. Tower told me to turn left, climb to 3000’ and proceed toward the CON VOR. After I requested another approach, I was handed back to approach control and again told to head back to the CON VOR and hold 10 south on the 172 degree radial. That was good as it essentially placed us right back at the start of the final approach on the localizer, where we had been only a few minutes earlier.

So, long story short. Divine providence intervened. As I was cleared for the second approach, I was told that a 727 aircraft was just taking off and that I should be aware of possible wake turbulence. Hmmm, I thought on that, realizing that in a zero wind situation on the ground the wake turbulence could persist for some time. I decided to press on and went through the same procedure as before. Intercepted the glide slope at the outer marker, gear and flaps, fuel ok, engines and props set, good luck. Well as luck would have it at about 500 or 600 feet of altitude and about ½ mile out the murk parted. The 727 that just left had apparently displaced enough fog so that I could see sufficiently ahead to successfully land. Shortly after I landed, the fog closed in again.

End of story. Persistence, flying by the rules and numbers, leaving one an out and a bit of good luck all blended together for a happy ending to the trip.