While too advanced for the phone at this stage, there is something called "direct inertial aiding" that solves this problem. Basically it uses the gyro to estim

While too advanced for the phone at this stage, there is something called "direct inertial aiding" that solves this problem. Basically it uses the gyro to estimate the position during a gps outage and then it can tell the GPS where to look in the sky for satellites. As it is, the gps has to scan the entire sky and it assumes nothing about its position. Even if you just passed under a bridge and only had a monetary outage. Direct Inertial Aiding makes pick-back-up times very small.