[Another more technical flying oriented post. This is a long post because there are many details to convey, so I will divide it into three parts.]
The Mission
We knew all along that the flight from Santiago, Chile/SCEL to Easter Island, Chile/SCIP would be one of the most logistically challenging flights for the whole trip mainly due to the distance. The total distance from Santiago to Easter Island is 2,030 NM (2,340 SM) and there is typically an average headwind component of approximately 25 KTS in early December. The combination of distance and headwind would make a non-stop flight impossible in our unmodified plane. Most smaller general aviation (GA) planes that fly to Easter Island (which is rare) use special auxiliary fuel tanks, but we wanted to do the flight in a "stock" airplane. Thus, we would need a fuel stop along the way and the only option on that route was the small airport on Robinson Crusoe Island, Chile/SCIR.
Robinson Crusoe Island has an AFIS and a plenty long enough runway for our plane, but no instrument approaches and, critically, no fuel. The only substantial information on the airport in the Chilean AIP is this VFR arrival chart....
Thus one key logistical hurdle would be getting fuel to Robinson Crusoe Island.
Fuel at Robinson Crusoe Island/SCIR
Fortunately for us, we had developed a close working relationship with the folks at the Aerocardal FBO in Santiago during the preparations for our January 2017 Antarctic flight. In particular, Jose G. in Aerocardal's dispatch/operations department led the charge in getting us both access to fuel and the required Chilean CAA permits to make the trip to Antarctica. Jose even went with us on the first and last legs of the Antarctic flight and thus we had developed a good relationship.
Giuseppe C initially worked to organize the fuel delivery, but when it turned out Giuseppe could not join us on the trip Josh took over the task of coordinating the fuel delivery at Robinson Crusoe. Josh got Jose and Aerocardal involved along with our contact on the island, Marcelo. Jose sprang into motion to help us get fuel delivered in barrels to Robinson Crusoe Island prior to our flight. It was very helpful that Josh is fluent in Spanish because this effort required a great deal of email communication that had to be clear.
After much back-and-forth communication, delivery of two barrels (about 110 gallons) of jet fuel to Robinson Crusoe Island was confirmed about one week before our flight. Turns out that getting fuel to the island is just half the battle - getting it to the airport is another challenge. The only town and pier suitable for cargo vessels on the island is on the opposite side of the island from the airport and there are no roads between the two.
The only way to get from town to the airport is by a 10 hour donkey ride or the more common 1.5 hour boat trip to a small jetty just below the airport.
In order to use the small airport jetty, tides must be taken into consideration which means the person handling delivery of fuel on the island, Marcelo, needed to know our ETA in advance. Problem was we could not predict which day we would conduct the flight until a couple of days in prior (see below).
Flight Planning - Robinson Crusoe Island
There were two big challenges to flight planning for this trip: 1.) the weather at Robinson Crusoe Island given it had no instrument approaches; and b.) the winds along the 1,623 NM (1,860 SM) route from Robinson Crusoe Island to Easter Island.
Robinson Crusoe Island airport lies in an area with Class G (uncontrolled) airspace up to 6,000 FT. Thus, ATC cannot issue any IFR clearance below 6,000 FT and you are basically "on your own" below 6,000. If it is a day with clear skies, no problem, just continue VFR after passing 6,000 FT. The bad news is this time of year Robinson Crusoe Island typically has broken to overcast skies during the morning period when we were scheduled to arrive. The good news is the ceiling is normally 2,000 FT or more and visibility is good below. So, the procedure for arriving on an overcast day is to descend over the ocean in IMC (but not on a flight plan) from 6000 FT to whatever altitude you are comfortable with (we decided on 1,000 FT above the ocean) and then proceed visually to the airport as shown on the visual approach chart above. If you are still IMC at your self-selected minimum descent altitude (MDA), then you turn away from the island and climb back to 5,000 FT and call Santiago Center (on HF) for a clearance to reenter controlled airspace and return to the mainland.
There is a terminal area forecast (TAF) for Robinson Crusoe Island airport, but it is typically issued just once a day at about 0730 local which is after our planned departure. So we would depend on the ECMWF forecast model of cloud bases and visibility for guidance as presented at Windy.com. The good news is we had plenty of fuel reserves for this leg of the flight. If we launched for Robinson Crusoe and could not land due to low clouds and/or visibility, we could easily return to Santiago. In other words, we had a good alternate. This was not the case with our next stop.
Flight Planning - Easter Island
Flight planning for Easter Island involved totally different considerations than Robinson Crusoe Island. Easter Island has a well developed airport with a long runway, plenty of jet fuel availability (no avgas), a control tower, and an ILS approach to the almost always used runway 10 along with various other non-precision approaches.
What Easter Island does not have is a good alternate. It is one of the most remote airports on the planet. The closet IFR airport approved as an alternate is almost 2,000 NM distant and the closest airport at all is more than 1,400 NM away. Thus fuel reserves are the big planning issue for Easter Island. Fortunately, weather at Easter Island in November/December is almost always VFR, so there is little risk of low clouds or limited visibility preventing a landing, but there is always the chance of passing thunderstorm, disabled aircraft on the runway, ot some other transient event that might requiring holding.
Getting the Permit to fly to Easter Island
Chile has a special set of rules for flying to Robinson Crusoe Island and especially Easter Island. A permit is required for a flight to Easter Island from mainland Chile even though it is technically a domestic flight. The rules are outlined in documents DAN 11-107 and DAN 14-06. We could only find Spanish versions of these documents, so once again Josh's Spanish language skills were valuable.
While the requirements to fly to Easter Island are several, the most limiting is the need to have three hours (180 minutes) of fuel reserve. Technically the document says a private operator might be issued a permit with less than three hours reserve if it can be proven the flight will not interfere with any commercial operations. Our impression is it would be difficult to get a permit without proving three hours reserve, but perhaps if the scheduled arrival time was well after all the commercial flights (typically 2-3 per day) had departed for the the day a permit might be issued. However, this might require paying overtime fees of about $900 per hour to keep the airport open beyond their normal schedule.
The Chilean CAA folks do not just take your word that you have the three hours reserve...you must prove it to them with detailed calculations. If your plane has extra non-standard fuel tanks (which we do not have), you also need to provide them with all the technical specifications and regulatory approvals related to the auxiliary fuel tanks.
In our case, I provided the CAA: 1.) a spreadsheet showing our maximum endurance at long-range cruise power (see below); and 2.) a computer generated flight plan based on projected winds for our intended flight day. Both showed more than 11 hours endurance and three hours reserve at a zero wind condition. With more than about a 10 KT headwind component the reserve dipped below three hours. Thus we needed to wait for a day with a forecasted headwind of 10 KTS or less.
Importantly, the reserve is considered fuel available at cruise altitude and at "normal" cruise power (long range cruise power for this flight). While altitude does not make much difference in reserve calculations in piston engine planes, it makes a big difference in turbine planes. The three hours reserve calculated at FL300 (30,000 FT) diminishes significantly flying a holding pattern a few thousand feet above the airport. Thus, if holding is required, it is important to make that decision before starting the descent from cruise altitude. "Going down to take a look" significantly compromises reserves.
The Chileans were satisfied with our calculations and issued our permit for flying to Easter Island Monday afternoon, November 26. That was a big relief because the whole trip depended on that flight as there were no other routing options in the southern hemisphere.
Based on wind and other weather forecasts, it appeared Wednesday, November 28 would be an almost ideal day for our flight to Easter Island...almost a net zero head component (even a small tailwind was forecast at times); a reasonable 2,000+ FT cloud base at Robinson Crusoe Island with good visibility below; and excellent VFR conditions at Easter Island.
The projected winds, fuel, and flight time as of Monday, November 26 for the flight from Robinson Crusoe Island to Easter Island assuming a departure on Wednesday, November 28....
Josh and I planned to sleep late on Tuesday, November 27 and then devote the rest of the day preparing to fly to Easter Island the next day assuming no significant adverse changes in the winds and weather forecast
This post is far too long already, so I will pick-up the story in the next post with the description of the actual flight along with photos and videos.
