OK.
Then so far it appears that "Buddy breathing" is the only thing anyone has come up with that was taught that is no longer taught/required that may make diving less safe and even that is being debated by some.
Maybe folks will come up with more!
It gets more complicated than that.
During an air sharing ascent, the out of air diver probably will not have the ability to use the auto-inflator until reaching shallow water when the remaining small pressure of air becomes unlocked by decreasing pressure. Until then, the out of air diver will have to orally inflate the BCD for buoyancy. Even a direct ascent to the surface may result in a diver venting too much air from the BCD and needing to replace it. Buddy-breathing is also a great building block skill that allows divers to learn to time removing a regulator from the mouth under stress of an air-sharing ascent. At PDIC, we teach buddy-breathing to include buddy-breathing BCD ascents in which students exhale into the BCD rather than into the water column, while passing a second stage back and forth, to maintain correct buoyancy while venting from the BCD on the way up. As a training exercise, done repeatedly, it helps because a diver who can pass a reg while buddy breathing and while using only the BCD to maintain ascent rate and buoyancy control will be more likely to be able to remove an octo from his mouth and add air to his BCD during an air sharing ascent or return swim if needed.
Building block skills and training beyond the level expected during game day will make dealing with a true emergency easier. So, it is not just what is taught, but how something is taught, and the proficiency to which it can be performed that is important.
Flooded mask and no mask skills are important because divers in close proximity in a stress situation like an air share, are more likely to experience a flooded or lost mask than when further apart during normal diving. Rather than becoming an emergency or a reason for panic, a flooded or lost mask is merely a nuisance situation that should easily be managed. While rare, it is possible. Why let a nuisance become a disaster? Plus, by training under such conditions, the management of a classic out of air or low on air situation that requires air sharing with an octo will be more easily handled with a greater degree of proficiency.
In my advanced, leadership and tech classes, all I need to do is ask students to share air with an octo and hold a 3 minute safety stop at 15 feet and it drives the point home to everyone from OW divers to course directors that they cannot proficiently share air.
All scuba skills should be performed with both a flooded mask and without a mask. This is not always taught.
PDIC OW divers can perform a double no mask, BCD non-kicking ascent, while buddy-breathing. Why? Mostly so they can easily share air when they have masks and the octo is working. But, also, so that the worst case scenario can be managed. Most of my tech classes are filled with PADI and NAUI DM's and instructors and so far not a single leader from these agencies has been able to share gas at a 15 foot safety stop for 3 minutes without a line.
That's not a condemnation of the agencies as much as it is saying that the most critical emergency skill we have - sharing gas - even with an octo - is not over learned, over trained, and developed to proficiency even in dive leadership.
Try this drill with your buddy:
At 30 feet, signal out of gas and manage the emergency. Using a stop watch, thumb the dive and time your ascent and your safety stop to the surface without using a line. Try to maintain horizontal trim and stay in one spot facing each other without using your hands or swimming in circles around the water column. Your entire ascent should take exactly 4 minutes - 1 minute for the total ascent distance 30 feet at 30 feet per minute and 3 minutes at 15 feet for the safety.
Your proficiency at this will tell you where your skill level for air sharing lies.
Extra credit: Once you've dialed-in this skill, remove a mask from the out of gas diver and do the exercise. Right hand to right hand to keep the left free to adjust buoyancy, guide the buddy to the surface. Thumb up = add gas. Thumb down = dump gas. Hand moving side to side with palm flat = level off. Do this with both divers being out of gas and with no mask. Now, return to practicing this exercise with both diver's being able to see. Have you improved?
Graduation: Repeat this exercise with both divers without a mask. Count in "Mississippi's" like in touch football, "One Mississippi, Two Mississippi, Three Mississippi ... " until you reach 30 Mississippi. This should be about 15 feet. Count 3 minutes of deco with the leader extending the pinky of the buddy upward to indicate deco and then extend 1, 2 or 3 fingers to indicate number of minutes remaining. After reaching the surface, check your time. Have another buddy (preferable with rescue, DM or instructor training) act as lifeguard and referee. Practice until it's proficient.
Now, repeat the regular air-sharing exercise with both divers having a face mask. How did you do?
Grad School: Repeat air sharing exercise while buddy-breathing with a single primary. Practice until proficient. Return to air sharing with octo. How did you do?
Post Graduate Work: Repeat buddy-breathing exercises with one diver without a mask and with both divers without masks. Practice until proficient. How did you do?
How do you now feel about your ability to share air?
The goal is two divers able to ascend face to face horizontally without sculling hands or feet on time and hold a safety stop exactly at 15 feet without a line. Imagine how easy it will be to do in real conditions with acceptable margins of buoyancy and skill error now.
The PADI and NAUI leaders I mentioned, were humbled, practiced this and now teach it to their students.
"A very smart man changed the way I dive and teach," remarked one guy who was a NAUI DM in my class, who is a NAUI instructor today.
