Narrative:

We departed; we were given clearance to climb to 17;000ft and best rate through 11;000. Soon after; we were given best rate through 12;000. Upon passing 10;000; I set a speed restriction of 250/12000 in FMC; selected econ; and due to the 120-cost index; per the release; lowered the climb speed to 320kts from 335kts. Eventually we were given a climb to somewhere in the upper 20s. Next came a clearance to climb to a higher altitude in the lower 30s. At around 27;000ft; I noticed the autopilot starting to chase the speed and was doing small vertical oscillations in the attempt. I made a comment to my first office (first officer) about the autopilot having issues. Knowing the 737 has a few issues with VNAV; it wasn't anything more than slightly unusual at this time. These oscillations continued to get more extreme. I told first officer that I was going to switch the vertical mode from VNAV to flch (flight level change). After doing this; the oscillations didn't get any better. I then told him I was going to try V/south; assuming if I could get the aircraft to stop chasing the speed the oscillations would go away. With no relief in sight; I then told first officer; 'I can't take this anymore; I'm turning the autopilot off;' expecting full well for everything to be fine and blaming the whole thing on a quirky autopilot. As soon as I turned the autopilot off; I discovered that I could barely move the yoke forward and back. As first officer would later say; it was like pushing the yoke through wet; soon to be dry; concrete. At first I thought; this can't be; it must be me. I told him I can't move the elevator; you try. He couldn't move it with any effectiveness either. With further force; and being as gentle as we could; we could move it; but with minimal effect. It felt like manual reversion in the simulators that I have done many times; but with slightly less effect. At this point; I checked the roll and yaw axis and everything felt normal. I didn't push the rudder too much either way; as I wasn't sure what was going on with the tail on this airplane. We also determined that the stabilizer trim was working as normal; which became our primary way to control our vertical axis. As soon as we determined we had this flight control issue; we notified ATC as an emergency. We were equal distance from ZZZ and ZZZ1; with ZZZ1 being on the nose and ZZZ behind us. We asked ATC what the runway length and winds were in ZZZ1. Knowing that ZZZ1 would have big; long; and wide runways. ATC informed us that the runway that lined up with the 8kt wind was over 12000ft. We informed ATC that's where we wanted to go. During this entire time; we never had any indication of anything being wrong with the aircraft except from physically struggling to move the elevator. Hydraulic quantity and pressure were normal. I then asked first officer to find me a checklist in the QRH that had something to do with what was going on. The only checklist he could find was the manual reversion checklist; which related to hydraulic pressure or quantity loss. I asked him to look at every flight control cover and switch and make sure they were all in their normal positions. He assured me everything was where it should be. We then inquired as to the winds in ZZZ as I knew it would be much easier to handle the passengers. ATC advised us that the winds were gusting up to 30kts. ZZZ1 was our final decision. At this time; I asked first officer to talk to the flight attendants and inform them of our situation. I asked him to give them the full briefing and prepare for possible evacuation on the runway. Soon after the event started; we slowly bleed off speed and descend. Not wanting to make any abrupt changes; we slowly reduced the speed to 250kts. I noticed as the speed decreased we would gain a little bit of elevator authority. I asked first officer to take the aircraft while I made a short public address to the passengers. After taking controls back; I asked first officer to ask ATC to notify the company as the 737 is not sat phone equipped; and making any attempt at this point to talk to company and maintenance would be a long process and I couldn't afford to be without the first officer. We asked ATC for the ILS frequency and were informed that the 12000 ft. Runway didn't have an ILS only the 9600 ft. Runway. With only a 4 or 5kt crosswind; and very much needing vertical guidance; we decided to switch to runway 9600 ft. At ZZZ1. We then asked for the ILS frequency; course; and FAF name. We extended our centerline off the FAF to give us better situational awareness as we didn't have any charts to look at. It was daylight and 'clear and a million.' we informed ATC that we needed a 20-mile straight in to work through this problem. I wanted to check the aircraft state in every configuration and feel how it was responding at these different settings.the flight attendants called us back at some point and told us that the cabin was prepared. We relayed all pertinent information to ATC and requested crew fire rescue to be standing by. There was not a whole lot of briefing the norms for first officer and I as we had no approach charts and were committed to the landing. It was briefed that I may need him at anytime; and especially in the flare; to help with the flight controls. We were under landing weight and first officer referenced the QRH landing data. We selected max brakes as a precaution. We received our long final and slowly configured the airplane. After each flap setting and subsequent speed reduction; the elevator became easier to use. It was based on this that I wanted to use a flaps 30 landing and a lack of familiarity with flaps 40 from reducing the speed further. After final configuration with flaps 30; I decided that I had enough elevator movement to make a safe landing without the need for the brace command. Upon reaching the flare; I asked first officer to help me pull back as the flight controls were extremely heavy. We made a somewhat 'normal' touchdown based on the circumstances. Auto brakes kicked in and acted normal. As I disengaged the autobrakes at a slow speed; the brakes felt like they barely worked. I asked first officer to feel them once when we had slowed to around 5kts and he agreed. We stopped the aircraft in the middle of [the] runway. The fire chief did a visual inspection of the aircraft and gave us a thumbs up. Initially we were trying to coordinate a tow to the apron; but informed ATC we were going to try a very slow taxi and if we had any problems would need to be towed. We proceeded to taxi very slowly and check the brakes immediately to ensure their usability. We then taxied to a passenger area and parked the aircraft. Once at the gate; I made another brief public address and asked first officer to please check on passengers and flight attendants. One extremely important note is that when we first got to the airplane; we were soon greeted by a mechanic asking us if everything was okay. We stated that we had just got there and hadn't had time to look around. He then noticed that the left hydraulic quantity was at 106 and the right at 80. He asked if we wanted him to transfer hydraulic fluid; we said sure. For 5 minutes; he was transferring without the left side going down at all but the right side was going up. I asked how that was possible and he said the gauge only goes to 106 and it was 'way over filled.' it took him over 10 minutes to balance the levels with the right ending up around 98 and the left around 100. It may be completely coincidental that a mechanic is working on our hydraulic system and an hour later; we have a major problem with the elevator. It almost felt like air was in the elevator hydraulic line instead of fluid.

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Original NASA ASRS Text

Title: B737NG flight crew reported difficulty moving the elevator controls during climbout; consequently diverting and landing in emergency condition.

Narrative: We departed; we were given clearance to climb to 17;000ft and best rate through 11;000. Soon after; we were given best rate through 12;000. Upon passing 10;000; I set a speed restriction of 250/12000 in FMC; selected Econ; and due to the 120-cost index; per the Release; lowered the climb speed to 320kts from 335kts. Eventually we were given a climb to somewhere in the upper 20s. Next came a clearance to climb to a higher altitude in the lower 30s. At around 27;000ft; I noticed the autopilot starting to chase the speed and was doing small vertical oscillations in the attempt. I made a comment to my First Office (FO) about the autopilot having issues. Knowing the 737 has a few issues with VNAV; it wasn't anything more than slightly unusual at this time. These oscillations continued to get more extreme. I told FO that I was going to switch the Vertical mode from VNAV to FLCH (Flight Level Change). After doing this; the oscillations didn't get any better. I then told him I was going to try V/S; assuming if I could get the aircraft to stop chasing the speed the oscillations would go away. With no relief in sight; I then told FO; 'I can't take this anymore; I'm turning the autopilot off;' expecting full well for everything to be fine and blaming the whole thing on a quirky autopilot. As soon as I turned the autopilot off; I discovered that I could barely move the yoke forward and back. As FO would later say; it was like pushing the yoke through wet; soon to be dry; concrete. At first I thought; this can't be; it must be me. I told him I can't move the elevator; you try. He couldn't move it with any effectiveness either. With further force; and being as gentle as we could; we could move it; but with minimal effect. It felt like manual reversion in the simulators that I have done many times; but with slightly less effect. At this point; I checked the roll and yaw axis and everything felt normal. I didn't push the rudder too much either way; as I wasn't sure what was going on with the tail on this airplane. We also determined that the stabilizer trim was working as normal; which became our primary way to control our vertical axis. As soon as we determined we had this flight control issue; we notified ATC as an emergency. We were equal distance from ZZZ and ZZZ1; with ZZZ1 being on the nose and ZZZ behind us. We asked ATC what the runway length and winds were in ZZZ1. Knowing that ZZZ1 would have big; long; and wide runways. ATC informed us that the runway that lined up with the 8kt wind was over 12000ft. We informed ATC that's where we wanted to go. During this entire time; we never had any indication of anything being wrong with the aircraft except from physically struggling to move the elevator. Hydraulic quantity and pressure were normal. I then asked FO to find me a checklist in the QRH that had something to do with what was going on. The only checklist he could find was the manual reversion checklist; which related to hydraulic pressure or quantity loss. I asked him to look at every flight control cover and switch and make sure they were all in their normal positions. He assured me everything was where it should be. We then inquired as to the winds in ZZZ as I knew it would be much easier to handle the passengers. ATC advised us that the winds were gusting up to 30kts. ZZZ1 was our final decision. At this time; I asked FO to talk to the flight attendants and inform them of our situation. I asked him to give them the full briefing and prepare for possible evacuation on the runway. Soon after the event started; we slowly bleed off speed and descend. Not wanting to make any abrupt changes; we slowly reduced the speed to 250kts. I noticed as the speed decreased we would gain a little bit of elevator authority. I asked FO to take the aircraft while I made a short Public Address to the passengers. After taking controls back; I asked FO to ask ATC to notify the company as the 737 is not sat phone equipped; and making any attempt at this point to talk to company and maintenance would be a long process and I couldn't afford to be without the FO. We asked ATC for the ILS frequency and were informed that the 12000 ft. runway didn't have an ILS only the 9600 ft. runway. With only a 4 or 5kt crosswind; and very much needing vertical guidance; we decided to switch to runway 9600 ft. at ZZZ1. We then asked for the ILS frequency; course; and FAF name. We extended our centerline off the FAF to give us better situational awareness as we didn't have any charts to look at. It was daylight and 'clear and a million.' We informed ATC that we needed a 20-mile straight in to work through this problem. I wanted to check the aircraft state in every configuration and feel how it was responding at these different settings.The flight attendants called us back at some point and told us that the cabin was prepared. We relayed all pertinent information to ATC and requested Crew Fire Rescue to be standing by. There was not a whole lot of briefing the norms for FO and I as we had no approach charts and were committed to the landing. It was briefed that I may need him at anytime; and especially in the flare; to help with the flight controls. We were under landing weight and FO referenced the QRH landing data. We selected max brakes as a precaution. We received our long final and slowly configured the airplane. After each flap setting and subsequent speed reduction; the elevator became easier to use. It was based on this that I wanted to use a flaps 30 landing and a lack of familiarity with flaps 40 from reducing the speed further. After final configuration with flaps 30; I decided that I had enough elevator movement to make a safe landing without the need for the brace command. Upon reaching the flare; I asked FO to help me pull back as the flight controls were extremely heavy. We made a somewhat 'normal' touchdown based on the circumstances. Auto brakes kicked in and acted normal. As I disengaged the autobrakes at a slow speed; the brakes felt like they barely worked. I asked FO to feel them once when we had slowed to around 5kts and he agreed. We stopped the aircraft in the middle of [the] Runway. The fire chief did a visual inspection of the aircraft and gave us a thumbs up. Initially we were trying to coordinate a tow to the apron; but informed ATC we were going to try a very slow taxi and if we had any problems would need to be towed. We proceeded to taxi very slowly and check the brakes immediately to ensure their usability. We then taxied to a passenger area and parked the aircraft. Once at the gate; I made another brief Public Address and asked FO to please check on passengers and flight attendants. One extremely important note is that when we first got to the airplane; we were soon greeted by a mechanic asking us if everything was okay. We stated that we had just got there and hadn't had time to look around. He then noticed that the left hydraulic quantity was at 106 and the right at 80. He asked if we wanted him to transfer hydraulic fluid; we said sure. For 5 minutes; he was transferring without the left side going down at all but the right side was going up. I asked how that was possible and he said the gauge only goes to 106 and it was 'way over filled.' It took him over 10 minutes to balance the levels with the right ending up around 98 and the left around 100. It may be completely coincidental that a mechanic is working on our hydraulic system and an hour later; we have a major problem with the elevator. It almost felt like air was in the elevator hydraulic line instead of fluid.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.