So much about this airline is a mystery.
The lone ghost-white aircraft – with no logo or name displayed – sits in the far corner of the airfield outside Cairo International Airport. The aged twin-engine Boeing 737 could be mistaken for a CIA plane used for extraordinary rendition of al-Qaeda suspects; it even resembles the DC-2 that flew to Shangri-La.
The plane, in fact, is the entire fleet of the phantom airline: Air Sinai, a semi-secret division of Egypt Air.
Though thousands of people have tried and failed to get a seat on this plane, it is possible to do so. It's just not easy.
Air Sinai was created in 1982, right after the Israel-Egypt peace treaty went into effect. As part of the normalization of relations between the two former enemies, the treaty called for the national airline of each country to fly regularly in and out of the other country's main international airport.
Israel's El Al airline happily complied, taking often-full flights of internationals and curious Israelis to the Egyptian capital.
The owner of Egypt Air, the government of Egypt, was a little squirmier. To fulfill the terms of the treaty without appearing to do so to its citizens and to others from Arab countries to which it flew, Egypt Air created a new division – Air Sinai, operating under the International Air Transport Association code of 4D.
This airline would fly to and from Tel Aviv every week, without forcing Egypt Air to list the destination among its flights, or on its maps.
For a time, the airline prospered and even offered flights to and from Tel Aviv by way of Sharm el Sheikh, the Sinai Red Sea resort area that Israelis were most reluctant to leave behind when they returned the Sinai to Egypt as part of the treaty.
Air Sinai flights were suspended in 2002, during the Palestinian uprising, or intifada, and resumed on a smaller scale.
When El Al suspended its flights this spring owing to the popular uprising in Egypt, Air Sinai became the only choice for a direct flight between Tel Aviv and Cairo, assuming one could get a seat.
It's hard to even find Air Sinai online, and it's impossible to book a seat between Tel Aviv and Cairo. Pursuing any of the online discount brokers that purport to offer Air Sinai tickets will lead the unsuspecting traveller either to a message that says there is "no service" between the two cities, or will route the person through Jordan on Royal Jordanian Airlines.
Checking on the parent Egypt Air's website, there is no mention whatsoever of Air Sinai; Tel Aviv can't even be successfully entered in the destination box.
Air Sinai's telephone number is unlisted.
It's left to a handful of traffickers – sly travel agents and hotel concierges in Israel and Egypt – to get hooked up. An envelope of cash is sent to an unmarked office and, in return, comes an odd, horizontal yellow booklet that resembles an airline ticket of a bygone era.
And there it is: Flight 4D-55 to Cairo; the pre-1948 address of the mysterious booking agent is given as Jerusalem, Palestine.
Armed with this unusual document, departing from Tel Aviv's Ben Gurion International Airport poses little problem – other than the feeling that 4D's little lineup of passengers is being overlooked by the Israeli security staff who are interrogating most other flights' passengers ahead of yours.
Departing from Cairo, a long wait for security is the least of the troubles.
Arriving at Cairo airport's new Terminal 3, the Air Sinai-bound passenger finds no reference to the flight on overhead departure monitors. A uniformed airport official actually directed this reporter to a different terminal (the one to which El Al used to fly).
Pressing ahead blindly as far as the airline counters, there still is no sign indicating Air Sinai; none of the Egypt Air counters lists Tel Aviv as a destination. However, an airline official eventually directs the traveller to an Egypt Air lineup for flights to Amsterdam and Rome.
Sure enough, the passenger is rewarded with an Egypt Air boarding pass and baggage claim for Flight 4D-54 to . . . Tel Aviv.
Passengers would be well-advised to go directly to the gate, do not pass by the lunch counter, do not collect any duty free. Being right at the gate is the only way to know when the Air Sinai flight is ready to board. While announcements for departing flights from all other airlines are given over the booming PA system, there's no call for Flight 4D-54.
Finally on board the half-full flight – most passengers seem to be on a holy land tour, another suggestion of Shangri-La.
Curiously, for all the subterfuge, the inside of the aircraft is full of Egypt Air symbols. The flight attendants wear EA uniforms, the napkins bear the EA logo, and the magazine tells EA stories.
Even the pre-flight announcement in Arabic and English says: "Egypt Air welcomes you onboard Flight 4D-54 to Tel Aviv . . ." (They probably figure that, since their cover is blown, they might as well get credit for fulfilling the treaty.) Up and away, Flight 4D-54 disappears into the clouds.
Some folks say it's up there still.