Liverpool why the altitude call on departure

[magpienja]

Hi all my local airfield is Liverpool EGGP, noticed for some time now that aircraft on departure are asked by the tower controller about 20-30 seconds after take off to confirm passing altitude, anybody know the reason for this.

Nick.

[almost professional]

my guess is that the tower ATCO is validating and verifying the transponder code on the departure before transfering to area control(its what we do too) ,using the ATM in the tower-it saves the approach controller from having to do it

[No_Speed_Restriction]

sounds about right because whenever we depart and we then are asked to confirm our altitude we then get transferred to MAN. sounds to me like an altitude verification scheme of some kind.

[magpienja]

Thank you guys all explained now.

Regards Nick.