He called on Ryanair to respond swiftly to the request for a signed document as the union does not want "to be in an industrial action phase".
VC said in advance of the meeting that it was looking for reassurances that Ryanair was genuine in its promise to recognize unions and threatened action if it turned out to be a tactic to delay strikes beyond Christmas.
The Dublin-based carrier met union representatives in Dublin on Tuesday, after Chief Executive Officer Michael O'Leary reached out to Ryanair's fledgling pilot organizations last week in a softening of a longstanding anti-union stance as the company's first-ever strikes loomed.
IMPACT said it would meet Ryanair on Tuesday evening, and hoped the suspension of industrial action would remove any uncertainty for passengers intending to travel on Wednesday.
It said it will recognise these unions as long as they establish committees of Ryanair pilots to deal with Ryanair issues, as Ryanair will not engage with pilots who fly for competitor airlines in Ireland or elsewhere.
"This is disappointing given all that's been said in the media over the last five days", they said in a joint statement.
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"If anything it accentuates the Ryanair model", he said.
Arriving for the meeting, Mr Harbor said they expected the company would confirm its decision to recognise the union for negotiating purposes.
The company said it will meet with other EU pilot and cabin crew unions in the New year.
The low-priced carrier said it was making the move to avoid "widespread customer disruptions over Christmas".
"We have meetings with the German unions tomorrow and Portuguese on Thursday, and we have meetings set up throughout January", he said.
The news came ahead of Ryanair's meeting later in the day with Impact, the union representing Irish pilots.