The effects of chirp phase errors are discussed in terms of their effect on the altimeter return. Firstly we describe previous methods of analysis in the context of the required height precision of the altimeter, and show that the Taylor series represents a more exact approach to modelling such errors. The effect on the measured height of each of the coefficients is ascertained and a simple proof shows that the contributions to the height error from each coefficient merely add. Finally, a critical assessment of the effects of these errors is undertaken.