The sky really is the limit: Our top five rare airmail stamps

On the day the first airmail delivery was made in 1918, we look at some classics of airborne philately

Today in 1918 the first official flight with airmail took off in Allahabad, India. Frenchman Henri Pequet flew the 6,500 letters 13 km, bringing them safely down in Naini.

Even in today's email era, the ability for a postcard to land on a doormat thousands of miles away in a matter of days, postal strikes excepted, makes the mind boggle.

Here's a look at our favourite five airmail related stamps and collections.

The Inverted Jenny

This rare specimen, produced on May 10, 1918 is arguably the most famous invert error in philately. The Curtiss JN-4 airplane was not known for its aerobatic displays but here it was, flying upside down on the 24c US postage airmail stamp. Only 100 of the stamps are thought to exist.

A mint specimen sold for $825,000 in 2007 at a Heritage Auction Galleries sale, making it the world's most expensive air mail stamp ever auctioned, although blocks of the stamp have sold for more.

Only 100 of the Inverted Jenny stamps were produced

The Black Honduras

The Black Honduras is a rarity from 1925, the first year the Central American country issued airmail stamps. Only two copies of this stamp are currently known. A specimen was unsold with a $100,000 reserve in 1999.

The Jerry Santangelo collection

As far as dedication to a collection goes, Jerry Santangelo went to greater depths than most. His collection of interrupted mail was both unusual and comprehensive. Santangelo recovered mail from plane and train crashes and ship wrecks right up until his death in 2009.

In December 2010 a large number of these items went to auction through Grosvenor Auctions for very modest prices. The collection included items from a Catapult plane forced down in the Scilly Isles and a hot air balloon that jettisoned its bag of mail in 1870 after being blown off course over Norway.

Gronchi Rosa specimens

Although not an airmail stamp, these Italian 1961 specimens, depicting an airplane flying over the Atlantic, are extremely rare. The 205 lira stamps were produced to commemorate President Giovanno Gronchi's trip to South America but incorrectly depicted the Peru-Ecuador border - not good for South American relations. The mistake was quickly corrected.

Mexican 1928 25c brown carmine and slate green

Running short on ink, the Mexican printer produced a limited run of brown carmine and slate green coloured airmail specimens in 1925 instead of the usual brown-carmine and brown. In terms of excitement it's not an upside down plane, but it is rare, and that's good enough for us.