[Champ]

pawn Код:

if(GetVehicleModel(plane) == 476)
    {
    GetVehicleVelocity(vehicleid,speed_x,speed_y,speed_z);
    format(alt_string,256,"Altitude: %0.2f meters",speed_z);
    TextDrawSetString(altitude[playerid], alt_string);
    }
    else
    {
        TextDrawSetString(altitude[playerid], " ");
    }

updated your snippet.
I think %i was showing the many digits.
Making it to 0.2f can reduce it.