If you do favor raising the limits, make sure you have trained in the kind of weather you will endorse your student to fly in. Don’t just train on nice days with calm winds then endorse your student for 25-knot crosswinds. Oftentimes the best teaching/learning experience comes on a day with lots of crosswind or marginal VFR conditions when you can barely see the airport from a four-mile final. Your endorsement is an important tool to keep students safe while they solo away from your direct supervision — use it wisely.
Brian Dillman is an associate professor of aviation technology at Purdue University. He’s a designated pilot examiner and holds airline transport pilot and certified flight instructor certificates with instrument and multiengine ratings. His research includes upset recovery training and digital aircraft data collection and utilization in a collegiate aviation environment. He says:
The setting and adherence of weather limits for any flight should ultimately be facilitated by the student pilots themselves. The concept of pilot in command is an easy one to understand, but one of the more difficult for students to incorporate and CFIs to relinquish. The establishment of weather limits is one area where the concept of PIC can be taught. The “go/no-go” decision is basically an exercise of determining if the weather is within legal limits and within the limits of the pilot and the aircraft. It is entirely possible that the weather is within limits of the regulations but outside the capabilities of either the pilot or the aircraft. Surface winds are the most common example of this potential. Since aircraft have a maximum demonstrated crosswind and not a specific limit, it falls upon the pilot to make the determination if the winds are within limits for a safe flight.
The same goes for visibilities and ceilings. It’s easy to say that student pilots shouldn’t go when the weather is less than a set amount of cloud height and visibility, such as 2,500 feet and 7 sm. It’s more difficult for students to make the decision as to whether or not it is safe to continue when they are within 10 nm of the airport and the weather has dropped to 6 sm. Six statute miles is less than 7 sm, but is it safe to continue? What about 5 sm? 3 sm? How about cloud ceilings? If the clouds drop to 2,000 feet, should the pilot continue? 1,500 feet? At what point does the pilot complete one of the most difficult maneuvers to initiate — the 180-degree turn?
Obviously this decision-making process takes time to accomplish and requires the skillful guidance of a competent CFI. A prudent step by the CFI is to place boundaries from which the student can operate. One of the most flexible limitations to be placed on the solo endorsement is “instructor verbal authorization required prior to solo flight.” This way, the CFI can ask the outcome of the “go/no-go” decision and then ask the most powerful question in the CFI toolbox: “Why?”