Calculate maximum deviation of quartz crystal
The correct estimate is a sum tolerance stackup of all variables for the crystal. (30+50+2 = 82ppm)

The 1st @ room temp is the just the initial tolerance of size of the crystal  to the designed  centre frequency. 

The 2nd is the angle of the cut of the XTAL in minutes (1/60th) of a degree that only affects the 3rd order slope at room temp, so both are additive.

So a XTAL tolerance of +/82 ppm over temp in 1 year does not include shock &amp; vibe nor C load error which adds to the room temp tolerance error and "could" be as little as 10 ppm with  10% caps but it depends on the slope of the cut and temp response.

other

In the early 90's we wanted to make a $1 TCXO for 928Mhz synth, so I digitized all the AT cut curves, generated 3rd order polynominals to compute any of them and created a test process to bin them using a 30 second (foam insulated copper FPC with thermistor  and 1/8W  heater R around XTAL) "mini oven" that tested offset @ +40'C then +70'C  which is a near "linear range". Then another guy created a tool to bin varicaps in 1 % bins, then when paired with the formulae, the TCXO could be compensated with DAC to Varicap within 1 PPM over -40~ +70'C range.  I generated another 3rd Ord polynomial to compute any Xtal curve based on Δf(T=40'C to 70'C). The programmer used the formulae  with thermistor readings to compute Varactor DAC voltage for $1 1ppm TCXO. Now you can buy them in bulk for this price.