Airmail Stamps. 
Ireland has an extensive airmail history. What is surprising is that the were no airports until the start of WWII. Early flights were from German trans-Atlantic steamers to Galway then to England and Germany. The RAF trained from sod fields in WWI. Belfast had the earliest scheduled service with the Great Western Railway’s Air Service to Liverpool in 1935. In the South, there were flights, but nothing like a scheduled air service.
The big change came in 1939 with the Pan Am Clipper service from the US to Southampton, England. These large seaplanes used a facility on the Shannon Estuary in Foynes for fuel and servicing en-route to Southampton, England to meet ocean liners. With the start of WWII a few weeks later, the American flights terminated in Foynes, since even though America was neutral, flying into the UK courted destruction by German fighters. Mail was transferred to British aircraft for the leg into England. Figure 1.
After WWII, the picture changed. The seaplanes were gone – replaced with land-based planes. Airports were built at Shannon and Dublin to serve as entry points to Europe. Irish stamps used for the airmail service were the current issues with the addition of an airmail etiquette.
Airmail stamps came upon the scene with the first issue of the 3d and 6d vales in April 1948. They were designed by R.J. King and printed by recess by Waterlow & Son, Ltd, and later by DeLa Rue. The designs were the Archangel Victor flying over various Irish landmarks. Figures 2 to 7.
VALUE LANDMARK COLOR
1d Cashel Sepia
3d Loch Derg Blue
6d Croagh Patrick Wine
8d Loch Derg Claret
1 s Glendalough Dark Green
1 s/3d Cashel Orange
1 s/5d Cashel Indigo
Like many other countries, the airmail stamps were phased out after 1955.
A few varieties and errors are known:
3d Position 6/3 Major re-entry
6d Position 4/3 Re-entryin lower right corner
8d Position 4/3 Dot on right hand of angel
1/3d Position 10/1 Extra feather on leading edge of left wing
1/5d Position 10/1 Cracked wall
1/5d Position 10/5 Retouch in cloud
See the Hibernian catalog for illustrations of above varieties
Even though they are no longer valid for mailing due to currency changes, these stamps are beautiful examples of the engravers’ skill and a memento of when traveling by air was a luxury.
Hibernian Handbook and Catalog of the Postage Stamps of Ireland compiled by Roy Hamilton-Bowen and Lee R. Wolferton.