Wednesday, February 17, 2010

Nevis, Night and Volcanos

We left Saturday on our first major family trip in the Mustang. Nevis, next to St Kitts in the Caribbean, was our destination. With all the US mid-Atlantic snow, and occasional thunderstorms in the Bahamas, the weather in Nevis was the least of my concerns. It's the dry season now with day after day of consistently beautiful skies. Just out of general curiousity, I checked the BBC Caribbean News site on the morning of our departure to find out that Montserrat, the closest inhabited island to the Southeast had released its largest volcanic ash plume in four years.

Volcanic ash is particularly toxic to turbine engines, more so than pistons. The higher heat of the turbine causes the blades to be covered with molten silicate leading to flameout and irrevocable engine damage (source). The National Weather Service's Volcanic Advisory Service predicted an ash plume heading northwest covered the islands of St Kitts and Nevis. There was no way I was going to fly into volcanic ash and risk a dual engine failure over water. The morning news had the potential to ruin weeks of planning. We elected to depart and go as far as our planned Exuma fuel stop, recheck conditions, and then perhaps find an alternative vacation location in the Caribbean far from Montserrat.

To further complicate matters, our first stop in North Carolina had received more snow the previous night than in the last 11 years. Even after calls to the FBO, we weren't certain if by the time we'd arrive the ramps would be clear and de-ice would be available. As a contigency, we planned alternatives further to south. Aviation provides great lessons in managing risk and thinking through alternatives.

In Exuma, we checked everything we could. Neither St Kitts nor Nevis have published weather, so we called both towers to crosscheck and verify. I'd rather speak to a controller who can see outside the window and know the arriving traffic rather than read a dry METAR. The commercial operators were flying and another jet had just landed so it seemed like the plume was not a significant factor.

Nevis limited us with one more constraint. We could not land any later than an half hour past sunset (6:45 AST / 5:45 EST PM). (An additional endorsement is required for night landings). We had planned to arrive 1 1/2 hrs before the cutoff but one small delay after another was cutting into that margin.

By the time we arrived in the St Kitts area, the sun had already set on the ground and there was broken cloud cover between 3000-5000 feet. Looking down into shadows at night over water, it's virtually impossible to determine what's water, cloud, or in this case, volcanic ash. The St Kitts Controller could not vector us below the clouds as there is no radar coverage. The only option is to fly an NDB approach into St Kitts and then circle to land at Nevis ("cleared for the NDB-A approach at St Kitts, report seeing Nevis in site").

It had been a long day, starting with the 5 am volcanic wake up call. Now, 13 hours later we had the following challenges:

  • Unfamiliar *type* of approach, over water, at night. How often do you fly an NDB approach with a circle to land at a different airport 10 miles away? Let's just say that this scenario was not covered at Flight Safety.
  • unfamiliar phraseology with a strong accent. It wasn't even clear to us which of the two NDB approaches the controller wanted us to fly.
  • Possible volcanic ash which was no longer visibly discernable.
  • Twice, the G1000 did not do what we expected while in GPS mode. It did not perform the course reversal, which had fortuntely backed up on the ADF. Once on final to Nevis, it tried to bring us back to the approach at St Kitts. We dumped the FD / Autopilot about 4 miles out.
  • No radar and weather reporting in the area.
  • A longing to be on the ground already.

We had the following powerful tools at our disposable:

  • a two person crew that worked well together and divided tasks efficiently.
  • With the exception of the miscoded approach, very capable avionics, providing moving map, terrain and synthetic vision so we knew we not at risk of hitting anything.

There was one final literal hurdle. Runway 10 at Nevis has a 500' displaced threshold due to a hill on the approach. It's always scary to look horizontally at warning lights, especially so in fading light.

We landed safely into a rapidly darkening tropical night, all the wiser with some important lessons. If you don't understand what a controller is saying, even with an accent, ask again until you are absolutely certain. Especially with the nagging get on ground feeling, take time to fully brief the approach and plan to stick with it. If the plan doesn't work out, take the necessary time to rebrief again.

After unnecessarily complicated immigration and an inbound customs inspection, we arrived at the hotel to enjoy a well earned meal. Staring out the next morning at the coconut palms and turquiose sea made the challenge of getting there all more worthwhile and satisfying.

No comments: