Errors in the manufacturing process


Production errors occur as the result of a mechanical malfunction or human error during the manufacturing process, i.e. from the printing until perforation, such as omitted color, color shift, double overprint, improper perforation, etc. Those errors occur randomly and inconsistently on numerous stamps and create varieties of the original stamp. A variety is a stamp differing in some visible detail with its standard image, caused by a fault in the manufacturing process.



Egypt – 1 October 1946 - First Middle East Regional Air Navigation Meeting

 The 30-millième deep green stamp, issued on 18 March 1941, was hastily overprinted to commemorate this ICAO conference. The quality of work was not of the highest class, thus giving rise to a number of inconsistent varieties and flaws (double or inverted overprint, off-centre imprint, missing characters, etc.), which must have been caused by clogged type, dirt on the press or smears of ink before it was dry.



Turkey – 17 October 1950 - Second Middle East Regional Air Navigation Meeting

Misperforations (Left: Imperforate vertically between pair; Right: vertical bisect)



Italy – 29 September 1952 - Diplomatic Conference on International Air Law

Correct design on the left.

Two varieties: aircraft touching the Coliseum (in the centre);

aircraft largely above the Coliseum (on the right).



Dominican Republic – 6 April 1956

Third Caribbean Regional Air Navigation Conference




Comoros – 22 November 1977

First Paris‑New York commercial flight of Concorde  

Double overprints: gold with silver inverted (on the left); gold with red inverted (on the right).


United Nations (New York) – 12 June 1978 - ICAO Safety in the Air

Colour shift (misalignment of one or more colour during the printing process) in main design has created white lines on the right and right-bottom sides of the ornaments.


Guyana – 6 September 1984 - 40th Anniversary of ICAO

Issued on 3 September 1973, the original stamp was overprinted and surcharged three times.

1.  On 25 June 1982, it was surcharged in dark blue with 330 AIR and overprinted in dark blue with Princess / of Wales / 1961‑1982 (for the 21st anniversary of Princess Diana).

2.      Then, it was surcharged vertically in black by 200 and overprinted vertically in black with G.A.C. / Inaug. Flight / Georgetown‑ / Toronto. The original value was obliterated with horizontal black bars. This stamp was in fact not issued and could be considered as an error: the acronym ICAO was missing.

3.  On 6 September 1984, the previous unissued stamp was overprinted vertically in dark blue with ICAO for the 40th anniversary of the Organization. The above shows an off-centred overprint.


Sudan – 7 December 1994 - 50th Anniversary of ICAO

Fair centring