The applicant will be tax exempt in his home country, but will be subject to a European tax.. Between 8 and 25 percent.
The salary in Cologne is slightly lower than in Bruxelles...
The allowances don't change the overall low salary, but this is an interesting job for someone coming to the end of his flying career as it includes a good pension scheme after (
AFAIK) 10 years with the Organisation..
But keep in mind those positions are only temporary, usually a 2 or 5 year contract including a 9 months probation period..